實(shí)驗(yàn)一：WindowsThreads多線程編程

1、實(shí)驗(yàn)一 ：Windows*Threads多線程編程模塊一：基礎(chǔ)練習(xí)4 編譯執(zhí)行， 輸出結(jié)果：簡(jiǎn)答與思考：1 寫(xiě)出修改后的HelloThreads的代碼。#include stdafx.h#include const int numThreads = 4;DWORD WINAPI helloFunc(LPVOID pArg) int myNum=*(int*)pArg);printf(Hello Thread %d n,myNum); return 0; int main()HANDLE hThreadnumThreads; int tNum10;for (int i = 0; i numThr

2、eads; i+) tNumi=i; hThreadi = CreateThread(NULL, 0, helloFunc, &tNumi, 0, NULL );WaitForMultipleObjects(numThreads, hThread, TRUE, INFINITE);return 0; 修改后結(jié)果2實(shí)驗(yàn)總結(jié)模塊二：臨界區(qū)實(shí)驗(yàn)2 編譯執(zhí)行， Pi的值為：3 編譯執(zhí)行，Pi的值為：簡(jiǎn)答與思考：1 如何進(jìn)行并行化的？請(qǐng)寫(xiě)出并行化的思路與具體的代碼。 / WinPi.cpp : 定義控制臺(tái)應(yīng)用程序的入口點(diǎn)/#include stdafx.h#include #include static

3、 long num_steps=1000000000; double step, pi;CRITICAL_SECTION gCS;/定義全局的臨界變量gCSconst int numThreads = 2;double dAllSum;DWORD WINAPI PiCalculationThread(LPVOID p)int j = *(int *)p;double dSum = 0;double dx;int ii;printf(This is the thread %d computing:n,j);for( ii = j ; ii num_steps ; ii+=numThreads )

4、 dx = (ii+0.5)*step; dSum = dSum + 4.0/(1.0 + dx*dx);EnterCriticalSection(&gCS);/進(jìn)入臨界區(qū)dAllSum += dSum;LeaveCriticalSection(&gCS);/離開(kāi)臨界區(qū)printf(The thread %d computation has finished:n,j);return 0;int _tmain(int argc, _TCHAR* argv) clock_t start1;clock_t stop1;start1= clock();/開(kāi)始計(jì)時(shí)HANDLE PiCalculation

5、numThreads;int tmpnumThreads; step = 1.0/(double) num_steps;InitializeCriticalSection(&gCS);for( int ia = 0 ; ia numThreads ; ia+ )tmpia = ia;PiCalculationia = CreateThread(NULL , 0 , PiCalculationThread , &tmpia , 0 , NULL);WaitForMultipleObjects (numThreads,PiCalculation,TRUE,INFINITE);DeleteCriti

6、calSection(&gCS);pi = step * dAllSum;printf(Pi = %12.9fn,pi);stop1 = clock();/停止計(jì)時(shí)printf(The time of calculation was %f seconds n,(double)(stop1 - start1)/1000.0);/輸出運(yùn)行時(shí)間2 在本實(shí)驗(yàn)中，哪些變量是需要保護(hù)的？采取什么方法實(shí)現(xiàn)的？dAllSum變量需要保護(hù)EnterCriticalSection(&gCS);/進(jìn)入臨界區(qū)dAllSum += dSum;LeaveCriticalSection(&gCS);/離開(kāi)臨界區(qū)printf

7、(The thread %d computation has finished:n,j);3是否可以對(duì)該并行化方案進(jìn)行進(jìn)一步的優(yōu)化？如何優(yōu)化？ 更改不同的線程數(shù)，計(jì)算加速比和效率，結(jié)果最好的那個(gè)線程數(shù)作為程序運(yùn)行的最佳線程數(shù)4 實(shí)驗(yàn)總結(jié)模塊三：事件實(shí)驗(yàn)3 編譯執(zhí)行， Result is The time of calculation was 19.55700seconds4 閱讀代碼，回答下面問(wèn)題。（1）主線程共創(chuàng)建 2 個(gè)子線程。（2）各子線程調(diào)用的函數(shù)各是什么？ Count threadProc （3）主線程等待 2 個(gè)子線程的執(zhí)行結(jié)束。6 改進(jìn)后的，編譯執(zhí)行，Result isThe t

8、ime of calculation was 15.122000 seconds簡(jiǎn)答與思考：1 在WINAPI threadProc(LPVOID par)函數(shù)中為什么用臨界區(qū)互斥了線程對(duì)threadCount的訪問(wèn)？為什么對(duì)于全局?jǐn)?shù)據(jù)變量sums的訪問(wèn)沒(méi)有互斥？WINAPI threadProc(LPVOID par)函數(shù) 使用多線程執(zhí)行的 threadCount 對(duì)于WINAPI threadProc(LPVOID par)函數(shù) 是共享變量，如果不使用臨界區(qū)互斥了線程對(duì)threadCount的訪問(wèn) 會(huì)造成數(shù)據(jù)沖突。2 簡(jiǎn)述源代碼中存在的問(wèn)題，詳述提出的改進(jìn)方案及相關(guān)代碼。/ ThreadE

9、vent.cpp : 定義控制臺(tái)應(yīng)用程序的入口點(diǎn)/#include stdafx.h#include #include #include #include #include #define NUMTHREADS 4#define SERIES_MEMBER_COUNT 100000HANDLE *threadHandles, masterThreadHandle,*eventHandle;CRITICAL_SECTION countCS;double *sums;double x = 1.0, res = 0.0;int threadCount = 0;double getMember(int

10、 n, double x)double numerator = 1;for( int i=0; in; i+ )numerator = numerator*x;if ( n % 2 = 0 )return ( - numerator / n );elsereturn numerator/n;DWORD WINAPI threadProc(LPVOID par)int threadIndex = *(int *)par);sumsthreadIndex = 0;for(int i=threadIndex; iSERIES_MEMBER_COUNT;i+=NUMTHREADS)sumsthread

11、Index += getMember(i+1, x); SetEvent(eventHandlethreadIndex);delete par;return 0;DWORD WINAPI masterThreadProc(LPVOID par)for( int i=0; iNUMTHREADS; i+ ) ResumeThread(threadHandlesi); / Start computing threads WaitForMultipleObjects(NUMTHREADS,eventHandle,TRUE,INFINITE); / busy wait until all thread

12、s are done with computation of partial sumsres = 0;for(int i=0; iNUMTHREADS; i+)res += sumsi;return 0;int _tmain(int argc, _TCHAR* argv) clock_t start, stop;threadHandles = new HANDLENUMTHREADS + 1; eventHandle = new HANDLENUMTHREADS + 1;sums = new doubleNUMTHREADS; start = clock();for(int i=0; iNUM

13、THREADS;i+)int * threadIdPtr = new int;*threadIdPtr = i;threadHandlesi = CreateThread(NULL, 0, threadProc, threadIdPtr, CREATE_SUSPENDED, NULL); eventHandlei = CreateEvent(NULL,TRUE,FALSE,NULL);threadHandlesNUMTHREADS = CreateThread(NULL, 0, masterThreadProc, NULL, 0, NULL);printf(Count of ln(1 + x)

14、 Mercators series members is %dn,SERIES_MEMBER_COUNT);printf(Argument value of x is %fn, (double)x); WaitForMultipleObjects(NUMTHREADS+1,threadHandles,TRUE,INFINITE); stop = clock();for(int i=0; iNUMTHREADS+1; i+ ) CloseHandle(threadHandlesi);delete threadHandles;delete eventHandle;delete sums; prin

15、tf(Result is %10.8fn, res);printf(By function call ln(1 + %f) = %10.8fn,x, log(1+x);printf(The time of calculation was %f secondsn,(double)(stop - start)/1000.0);printf(Press any key . );getch();3是否可以對(duì)該并行化方案進(jìn)行進(jìn)一步的優(yōu)化？如何優(yōu)化？ 應(yīng)該優(yōu)化 優(yōu)化*eventHandle;SetEvent(eventHandlethreadIndex);eventHandle = new HANDLEN

16、UMTHREADS + 1;4 實(shí)驗(yàn)總結(jié)模塊四：信號(hào)量實(shí)驗(yàn)3 確定串行版本項(xiàng)目為啟動(dòng)項(xiàng)，編譯執(zhí)行。 4 確定并行版本項(xiàng)目為啟動(dòng)項(xiàng)，編譯執(zhí)行。 修正后項(xiàng)目的輸出結(jié)果為：簡(jiǎn)答與思考：1 Serial.cpp與Threaded.cpp代碼執(zhí)行結(jié)果不一致的原因是什么？在多線程中 fd 和 TotalWords 為共享變量，在并發(fā)執(zhí)行的過(guò)程中會(huì)造成數(shù)據(jù)沖突。2 如何修改Threaded.cpp代碼？寫(xiě)出修改思路和關(guān)鍵代碼。#include stdafx.hHANDLE semaphore1,semaphore2;FILE *fd; int TotalEvenWords = 0, TotalOddWord

17、s = 0, TotalWords = 0;const int NUMTHREADS = 4;int GetNextLine(FILE *f, char *Line) if (fgets(Line, 132, f)=NULL) if (feof(f)return EOF; else return 1;int GetWordAndLetterCount(char *Line)int Word_Count = 0, Letter_Count = 0;for (int i=0;i132;i+)if (Linei!= )&(Linei!=0)&(Linei!=n) Letter_Count+; els

18、e if(Letter_Count!=0) if (Letter_Count % 2) TotalOddWords+; Word_Count+;Letter_Count = 0; else TotalEvenWords+;Word_Count+;Letter_Count = 0; if (Linei=0) break;return (Word_Count); DWORD WINAPI CountWords(LPVOID arg) BOOL bDone = FALSE ; char inLine132;while (!bDone) WaitForSingleObject(semaphore1,I

19、NFINITE); bDone = (GetNextLine(fd, inLine) = EOF); ReleaseSemaphore(semaphore1,1,NULL); if (!bDone) WaitForSingleObject(semaphore2,INFINITE); TotalWords += GetWordAndLetterCount(inLine) ; ReleaseSemaphore(semaphore2,1,NULL); return 0;int main()HANDLE hThreadNUMTHREADS; semaphore1 = CreateSemaphore(NULL,1,1,NULL); semaphore2 = CreateSemaphore(NULL,1