ÿþ<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=unicode" /> <meta http-equiv="Content-Language" content="en-us" /> <style> <!-- p.MsoNormal {margin-top:0mm; margin-right:0mm; margin-bottom:10.0pt; margin-left:0mm; line-height:115%; font-size:12.0pt; font-family:"Times New Roman","serif";} a:link {color:blue; text-decoration:underline;} a:visited {color:purple; text-decoration:underline;} p {margin-right:0mm; margin-left:0mm; font-size:12.0pt; font-family:"Times New Roman","serif";} --> </style> <title>The Windows Win32 thread synchronization tutorial: Concurrency and race conditions with program example</title> <meta name="keywords" content="system programming, Windows programming, technology, hardware, processors, tools, microprocessors, motherboard, download" /> <meta name="description" content="The Win32 concurrency and race conditions with program example" /> </head> <body lang="EN-US" link="#0000FF" vlink="#800080" topmargin="20" leftmargin="20" rightmargin="20" bottommargin="20"> <div class="Section1"> <h3 align="center" style="margin-bottom:0mm;margin-bottom:0; text-align:center; margin-top:0"><font size="5" face="Byington"> <span style="line-height:115%;font-weight:400">Windows Thread Synchronization 10</span></font></h3> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:0; margin-top:0">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt" align="center"> <script type="text/javascript"><!-- google_ad_client = "pub-8089415323104206"; google_ad_slot = "0761177910"; google_ad_width = 728; google_ad_height = 90; //--> </script> &nbsp;<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"><b> <font size="3" face="Arial"> <span style="font-size:12.0pt;line-height:115%; font-weight:bold">Concurrency and Race Conditions</span></font></b></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Race condition happens in many cases not just for threads and processes. A race condition occurs when two threads access a shared variable at the same time (concurrent). The first thread reads or accesses the variable, and at the &#39;same&#39; time the second thread reads the same value from the variable. Then the first thread and second thread perform their operations such as write, on the same value, and they race to see which thread can write the value last to the shared variable. The value of the thread that writes its value last is preserved, because the thread is writing over the value that the previous thread wrote and of course the first thread which wrote first will have incorrect result though the process was completed successfully. Each thread is allocated a predefined period of time to execute on a processor using such as round robin, interleaving and other methods. When the time slice that is allocated for the thread expires, the thread&#39;s context is saved until its next turn on the processor (context switching), and the processor begins the execution of the next thread.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> The reason for this is that the operating system decides which thread gets executed first. The order and timing in which the threads start are not all that important. So, a thread that is given &#39;least priority&#39; for example, by the operating system gets executed last. The most common symptom of a race condition is unpredictable values of variables that are shared between multiple threads. This results from the unpredictability of the order in which the threads execute. Sometime one thread wins, and sometime the other thread wins. At other times, execution works correctly. Also, if each thread is executed separately, the variable value behaves correctly. The race condition is a well known problem that is very difficult to debug. The following Figure tries to demonstrate the race condition, showing some possible interleaving of threads will results in an undesired final computation values.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt" align="center"> <img border="0" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode018.png" width="660" height="379" alt="Concurrency and Race Conditions illustration which produce incorrect result" /></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:0; margin-top:0">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:0; margin-top:0"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Can you imagine the result if there are more than two threads which are racing each other to access the shared resources such as in multithreading?</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"><b> <font size="3" face="Arial"> <span style="font-size:12.0pt;line-height:115%; font-weight:bold">Race Condition Program Example</span></font></b></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> The following code example tries to demonstrate the race condition (without any synchronization mechanism).</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Create a new empty Win32 console application project. Give a suitable project name and change the project location if needed.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="540" height="356" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode019.png" alt="Race Condition Program Example: Creating new console mode application C++ project" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Then, add the source file and give it a suitable name.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="540" height="400" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode020.png" alt="Race Condition Program Example: Adding new C++ source file" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Next, add the following source code.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">#include</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> <font color="#a31515"><span style="color:#A31515">&lt;windows.h&gt;</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">#include</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> <font color="#a31515"><span style="color:#A31515">&lt;stdio.h&gt;</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="#a31515" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:#A31515">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">const</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> DWORD numThreads = 4;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">DWORD WINAPI helloFunc(LPVOID arg)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">{</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// The call to the wprintf() will affect the thread time execution</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Retard program, I&#39;m thread %u\n&quot;</span></font>, GetCurrentThreadId());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// This is a dummy sleep to simulate tasks to be completed.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// The value also will affect the thread time execution</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// You may want to test different Sleep() values...</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sleep(1000);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">return</span></font> 0;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">}</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">int</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> wmain()</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">{</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; HANDLE hThread[numThreads];</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; DWORD dwThreadID, dwEvent, i;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">for</span></font>(<font color="blue"><span style="color:blue">int</span></font> i=0;i&lt;numThreads;i++)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hThread[i] = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)helloFunc,(LPVOID)dwThreadID,0,&amp;dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">if</span></font>(hThread[i] != NULL)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() is OK, thread ID is %u\n&quot;</span></font>, dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">else</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() failed, error %u\n&quot;</span></font>,GetLastError());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// Waits until one or all of the specified objects are</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// in the signaled state or the time-out interval elapses.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// 3rd param - TRUE, the function returns when the state of all objects in the lpHandles array is signaled.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// If FALSE, the function returns when the state of any one of</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// the objects is set to signaled. In the latter case, the return value</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// indicates the object whose state caused the function to return.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// 4th param - If INFINITE, the function will</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// return only when the specified objects are signaled.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dwEvent = WaitForMultipleObjects(numThreads,hThread,FALSE,INFINITE);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">switch</span></font> (dwEvent) </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp; { </span> </font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[0] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 0: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;First event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[1] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 1: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Second event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[2] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 2: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Third event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[3] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 3: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Fourth event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_TIMEOUT:</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Wait timed out...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// Return value is invalid.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">default</span></font>: </span> </font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Wait error %d\n&quot;</span></font>, GetLastError()); </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ExitProcess(0); </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">for</span></font>(i = 0;i&lt;4;i++)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">if</span></font>(CloseHandle(hThread[i]) != 0)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Closing the hThread[%d] handle is OK...\n&quot;</span></font>, i);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">else</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Failed to close the hThread[%d] handle, error %u...\n&quot;</span></font>, GetLastError());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">return</span></font> 0;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">}</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Build and run the project. The following are the sample outputs when the program was run many times.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="341" height="247" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode021.png" alt="Race Condition Program Example: A sample output demonstrating the race condition" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="349" height="235" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode022.png" alt="Race Condition Program Example: Another sample output showing the race condition" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> The following are sample outputs when we change the Sleep(1000); to the smaller value, Sleep(500);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="341" height="247" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode023.png" alt="Race Condition Program Example: A variation of the race condition" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="341" height="247" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode024.png" alt="Race Condition Program Example: Race condition in action" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="341" height="247" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode025.png" alt="Race Condition Program Example: unpredictable and undeterministic output" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> By editing the following part, the output should be clearer.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> & </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> & </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">for</span></font>(<font color="blue"><span style="color:blue">int</span></font> i=0;i&lt;numThreads;i++)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hThread[i] = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)helloFunc,(LPVOID)dwThreadID,0,&amp;dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">if</span></font>(hThread[i] != NULL)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() is OK, #%d thread ID is %u\n&quot;</span></font>, i, dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">else</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() failed, error %u\n&quot;</span></font>, GetLastError());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> & </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> & </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> The following screenshot is a sample output.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="365" height="247" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode026.png" alt="Race Condition Program Example: A better race condition demo" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Next, add/edit some part of the code as shown below, demonstrating the threads is doing some tasks on the global variable x.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">#include</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> <font color="#a31515"><span style="color:#A31515">&lt;windows.h&gt;</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">#include</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> <font color="#a31515"><span style="color:#A31515">&lt;stdio.h&gt;</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="#a31515" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:#A31515">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="green" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:green">// Global variable</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="green" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:green">// May use the &#39;volatile&#39; keyword instead of &#39;const&#39; to avoid</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="green" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:green">// the compiler optimization especially for the Release version</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">const</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> DWORD numThreads = 4;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">DWORD x = 0;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">DWORD WINAPI helloFunc(DWORD arg)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">{</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// The call to the wprintf() will affect the thread time execution</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Thread %u, arg = %u\n&quot;</span></font>, GetCurrentThreadId(), arg);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// Try updating the global variable, x</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; x = x + arg;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;x = %u\n&quot;</span></font>, x);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// This is a dummy sleep to simulate tasks to be completed.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// The value also will affect the thread time execution</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// You may want to test different Sleep() values...</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sleep(1000);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">return</span></font> 0;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">}</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" color="blue" face="Courier New"> <span style="font-family:&quot;Arial&quot;;color:blue">int</span></font><font size="3" face="Courier New"><span style="font-family:&quot;Arial&quot;"> wmain()</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">{</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; HANDLE hThread[numThreads];</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; DWORD dwThreadID, dwEvent, i;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">for</span></font>(<font color="blue"><span style="color:blue">int</span></font> i=0;i&lt;numThreads;i++)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hThread[i] = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)helloFunc,(LPVOID)i,0,&amp;dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">if</span></font>(hThread[i] != NULL)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() is OK, #%d thread ID is %u\n&quot;</span></font>, i, dwThreadID);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">else</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;CreateThread() failed, error %u\n&quot;</span></font>,GetLastError());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// Waits until one or all of the specified objects are</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// in the signaled state or the time-out interval elapses.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// 3rd param - TRUE, the function returns when the state of all objects in the lpHandles array is signaled.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// If FALSE, the function returns when the state of any one of</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// the objects is set to signaled. In the latter case, the return value</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// indicates the object whose state caused the function to return.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// 4th param - If INFINITE, the function will</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// return only when the specified objects are signaled.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dwEvent = WaitForMultipleObjects(numThreads,hThread,FALSE,INFINITE);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">switch</span></font> (dwEvent) </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp; { </span> </font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[0] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 0: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;First event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[1] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 1: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Second event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[2] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 2: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Third event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// hThread[3] was signaled</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_OBJECT_0 + 3: </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// TODO: Perform tasks required by this event</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Fourth event was signaled...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">case</span></font> WAIT_TIMEOUT:</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Wait timed out...\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">break</span></font>;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="green"><span style="color:green">// Return value is invalid.</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">default</span></font>: </span> </font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Wait error %d\n&quot;</span></font>, GetLastError()); </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ExitProcess(0); </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;\n&quot;</span></font>);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">for</span></font>(i = 0;i&lt;4;i++)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">if</span></font>(CloseHandle(hThread[i]) != 0)</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Closing the hThread[%d] handle is OK...\n&quot;</span></font>, i);</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">else</span></font></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; wprintf(L<font color="#a31515"><span style="color:#A31515">&quot;Failed to close the hThread[%d] handle, error %u...\n&quot;</span></font>, GetLastError());</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <font color="blue"><span style="color:blue">return</span></font> 0;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt;line-height: normal;text-autospace:none"><font size="3" face="Courier New"> <span style="font-family:&quot;Arial&quot;">}</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Rebuild and re-run the program several times. The following screenshots show the sample outputs.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="373" height="295" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode027.png" alt="Race Condition Program Example: sample output with thread doing something" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="365" height="295" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode028.png" alt="Race Condition Program Example: Another sample output with thread doing something" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="373" height="307" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode029.png" alt="Race Condition Program Example: More sample output with thread doing something" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="365" height="295" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode030.png" alt="Race Condition Program Example: Sample output with thread doing something but still cannot be predicted" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="373" height="307" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode031.png" alt="Race Condition Program Example: sample output with threads doing something in unordered manner" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="365" height="295" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode032.png" alt="Race Condition Program Example: sample output showing threads not in the order as in the program" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="373" height="307" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode033.png" alt="Race Condition Program Example: sample output of the unordered thread" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" align="center" style="margin-bottom:0mm;margin-bottom:.0001pt; text-align:center"><font size="3" face="Arial"> <span style="font-size: 12.0pt;line-height:115%"> <img width="373" height="307" src="threadprocesssynchronizationapis11_files/winthreadprocesssynchronizationcode034.png" alt="Race Condition Program Example: sample output with threads flow differently" /></span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%">&nbsp;</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt"> <font size="3" face="Arial"><span style="font-size:12.0pt;line-height:115%"> Can you see the &#39;funny&#39; outputs mainly the values of the global variable x? The outputs are not consistent, non-deterministic and time sensitive. Sometimes the outputs are in the sequence as expected; however, many times the outputs are not as expected. Keep in mind that the program (thread execution) runs without &#39;error&#39;.</span></font></p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <p class="MsoNormal" style="margin-bottom:0mm;margin-bottom:.0001pt">&nbsp;</p> <h3 align="center" style="margin-top: 0; margin-bottom: 0"> <script type="text/javascript"><!-- google_ad_client = "pub-8089415323104206"; google_ad_slot = "2156170134"; google_ad_width = 728; google_ad_height = 15; //--> </script> &nbsp;<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script></h3> <p align="center" style="margin-top: 0; margin-bottom: 0">&nbsp;</p> <h3 align="center" style="margin-top: 0; margin-bottom: 0"> <font face="Byington"><span style="font-weight: 400">&lt; <a title="The Windows Win32 thread synchronization tutorial: The interlocked variable access, interlocked API, interlocked singly linked lists and timer queues" style="color: blue; text-decoration: underline" href="threadprocesssynchronizationapis11_8.html"> Thread Synchronization 9</a> | <a title="The Windows Win32 thread synchronization techniques programming tutorials with program examples and code samples" style="color: blue; text-decoration: underline" href="threadprocesssynchronizationapis11index.html"> Thread Synchronization Programming</a> | <a title="The Win32 programming tutorial using Visual Studio, C and C++ languages" style="color: blue; text-decoration: underline" href="index.html"> Win32 Programming</a> | <a title="The Windows thread synchronization programming: concurrency, deadlocks, livelocks, liveness and deadlock example - The Dining Philosophers" style="color: blue; text-decoration: underline" href="threadprocesssynchronizationapis11_10.html"> Thread Synchronization 11</a> &gt;</span></font></h3> <p align="left" style="margin-top: 0; margin-bottom: 0">&nbsp;</p> <div align="center"> <script src="http://tag.contextweb.com/TagPublish/getjs.aspx?action=VIEWAD&cwrun=200&cwadformat=728X90&cwpid=527221&cwwidth=728&cwheight=90&cwpnet=1&cwtagid=82740"></script> </div> </div> </body> </html>