大連東軟信息學(xué)院-多核多線程-實(shí)驗(yàn)一

1-項(xiàng)目一：Windows*Threads多線程編程模塊一：基礎(chǔ)模塊4編譯執(zhí)行，輸出結(jié)果：簡答與思考：寫出修改后的HelloThreads的代碼。//HelloThreads.cpp:定?§義°?控?制?臺??§應(yīng)?|用??程¨?序¨°的ì?入¨?口¨2點(diǎn)ì?。?ê#include"stdafx.h"#include<windows.h>constintnumThreads=4;DWORDWINAPIhelloFunc(LPVOIDarg){ intmyNum=*((int*)arg);printf("HelloThread!Thread%d\n",myNum); return0;}intmain(intargc,_TCHAR*argv[]){ HANDLEhThread[numThreads];inttNum[numThreads]; for(inti=0;i<numThreads;i++) {tNum[i]=i; hThread[i]= CreateThread(NULL,0,helloFunc,&tNum[i],0,NULL); }WaitForMultipleObjects(numThreads,hThread,TRUE,INFINITE); return0;}項(xiàng)目總結(jié)。在主線程中循環(huán)調(diào)用CreateThread（）函數(shù)生成四個子線程分別去執(zhí)行helloFunc（）函數(shù)，并將線程的句柄保存在hThread數(shù)組中，CreateThread()的第四個參數(shù)給每個線程傳遞參數(shù)tNum獲取該線程號，由helloFunc（）的參數(shù)接收并指向內(nèi)容。由于主線程為每個子線程傳遞了不同的參數(shù)，所以通過子線程的執(zhí)行結(jié)果可以判斷出四個線程的執(zhí)行順序。這個實(shí)驗(yàn)要我們初步認(rèn)識了程序的并行化設(shè)計(jì)思想，為以后的并行化程序設(shè)計(jì)打下了基礎(chǔ)。模塊二：臨界區(qū)模塊3編譯執(zhí)行，記錄結(jié)果：Pi=Thetimeofcalculationwasseconds6編譯執(zhí)行，記錄結(jié)果：Pi=Thetimeofcalculationwasseconds7加速比：1.90503951，并行效率：0.47625988簡答與思考：1如何進(jìn)行并行化的？請寫出并行化的思路與具體的代碼。答：在程序中創(chuàng)建兩個子線程，另主線程等待所有的子線程執(zhí)行結(jié)束后退出。代碼：#include"stdafx.h"#include<windows.h>#include<time.h>staticlongnum_steps=1000000000;constintgNumThreads=2;doublestep=0.0,pi=0.0,sum=0.0;CRITICAL_SECTIONgCS;DWORDWINAPIthreadFunction(LPVOIDpArg){ intmyNum=*((int*)pArg); doublesum1=0.0,x; for(inti=myNum;i<num_steps;i+=gNumThreads){x=(i+0.5)*step;sum1=sum1+4.0/(1.0+x*x);#include<windows.h>#include<math.h>#include<time.h>#defineNUMTHREADS4#defineSERIES_MEMBER_COUNT100000HANDLE*threadHandles,masterThreadHandle,*eventHandles;CRITICAL_SECTIONcountCS;double*sums;doublex=1.0,res=0.0;intthreadCount=0;doublegetMember(intn,doublex){ doublenumerator=1; for(inti=0;i<n;i++) numerator=numerator*x; if(n%2==0) return(-numerator/n); else returnnumerator/n;}DWORDWINAPIthreadProc(LPVOIDpar){ intthreadIndex=*((int*)par); sums[threadIndex]=0; for(inti=threadIndex;i<SERIES_MEMBER_COUNT;i+=NUMTHREADS) sums[threadIndex]+=getMember(i+1,x); SetEvent(eventHandles[threadIndex]); //SignalMasterthreadthatonemoreprocessingthreadisdone //EnterCriticalSection(&countCS); //threadCount++;//LeaveCriticalSection(&countCS); deletepar; return0;}DWORDWINAPImasterThreadProc(LPVOIDpar){ for(inti=0;i<NUMTHREADS;i++)ResumeThread(threadHandles[i]);//Startcomputingthreads //while(threadCount!=NUMTHREADS){}//busywaituntilallthreadsaredonewithcomputationofpartialsums WaitForMultipleObjects(NUMTHREADS,eventHandles,TRUE,INFINITE); res=0; for(inti=0;i<NUMTHREADS;i++) res+=sums[i]; return0;}intmain(){ clock_tstart,stop; threadHandles=newHANDLE[NUMTHREADS+1]; eventHandles=newHANDLE[NUMTHREADS+1]; //InitializeCriticalSection(&countCS); sums=newdouble[NUMTHREADS];start=clock(); for(inti=0;i<NUMTHREADS;i++) { int*threadIdPtr=newint; *threadIdPtr=i; threadHandles[i]=CreateThread(NULL,0,threadProc,threadIdPtr,CREATE_SUSPENDED,NULL); eventHandles[i]=CreateEvent(NULL,TRUE,FALSE,NULL); } threadHandles[NUMTHREADS]=CreateThread(NULL,0,masterThreadProc,NULL,0,NULL); printf("Countofln(1+x)Mercator'sseriesmembersis%d\n",SERIES_MEMBER_COUNT); printf("Argumentvalueofxis%f\n",(double)x); WaitForMultipleObjects(NUMTHREADS+1,threadHandles,TRUE,INFINITE); stop=clock(); for(inti=0;i<NUMTHREADS+1;i++)CloseHandle(threadHandles[i]); deletethreadHandles; deleteeventHandles; //DeleteCriticalSection(&countCS); deletesums; printf("Resultis%10.8f\n",res); printf("Byfunctioncallln(1+%f)=%10.8f\n",x,log(1+x)); printf("Thetimeofcalculationwas%fseconds\n",((double)(stop-start)/1000.0)); printf("Pressanykey..."); getch(); return0;}3是否可以對該并行化方案進(jìn)行進(jìn)一步的優(yōu)化？如何優(yōu)化？線程在被創(chuàng)建時就執(zhí)行，不再去喚醒，“master”只需等待事件被激發(fā)，效率就會有所提高。4項(xiàng)目總結(jié)。模塊四：信號量模塊3這是串行代碼實(shí)現(xiàn)，編譯執(zhí)行，記錄結(jié)果。6編譯執(zhí)行并行版本，多次運(yùn)行，記錄結(jié)果：第1次執(zhí)行結(jié)果：第2次執(zhí)行結(jié)果：第3次執(zhí)行結(jié)果：10修正后項(xiàng)目的輸出結(jié)果為：簡答與思考：1SemaphoreS項(xiàng)目與SemaphoreT項(xiàng)目執(zhí)行結(jié)果不一致的原因是什么？在多線程中fd和TotalWords，TotalEventWords，TotalOddWords屬于共享變量，在并發(fā)執(zhí)行的過程中會造成數(shù)據(jù)沖突。fd對于每個線程是互斥的，是因?yàn)樵谖募羔樛乱恍懈淖儠r，不準(zhǔn)許其它線程對該操作有影響，不然就會造成該問題的計(jì)數(shù)結(jié)果不正確的現(xiàn)象；而TotalWords，TotalEventWords，TotalOddWords這幾個變量，是計(jì)算總的字符串個數(shù)，含有偶數(shù)數(shù)量字符的字符串的個數(shù)及含有奇數(shù)個字符的字符串的個數(shù)，毋庸置疑，它們也是共享資源，在對他們進(jìn)行累加時，要注意數(shù)據(jù)沖突。2如何修改SemaphoreT項(xiàng)目源代碼？寫出修改思路和關(guān)鍵代碼?？梢圆捎门R界區(qū)的方法去做，也可以采用信號量。信號量也是一種內(nèi)核對象，它可以對當(dāng)前的資源計(jì)數(shù)，這是與臨界區(qū)最大的不同，當(dāng)資源數(shù)量大于0時，等待該信號量的線程就可以獲得該資源得以繼續(xù)執(zhí)行。改進(jìn)方案：在代碼中應(yīng)用兩個信號量hSem1，hSem2，hSem1用于線程對文件指針fd的互斥，hSem2用于對全局變量TotalWords，TotalEventWords，TotalOddWords的互斥，對于每一個子線程，由于我們的思路是按行計(jì)算，然后累加的，對于偶數(shù)數(shù)量字符的字符串的個數(shù)以及含有奇數(shù)數(shù)量字符串的個數(shù)計(jì)算，要注意采取巧妙點(diǎn)的處理辦法。#include"stdafx.h"#include<windows.h>#include<stdio.h>#include<time.h>FILE*fd;intTotalEvenWords=0,TotalOddWords=0,TotalWords=0;HANDLEhSem1,hSem2;constintNUMTHREADS=4;intGetNextLine(FILE*f,char*Line){ if(fgets(Line,132,f)==NULL)if(feof(f))returnEOF;elsereturn1;}intGetWordAndLetterCount(char*Line){ intWord_Count=0,OddWords=0,EvenWords=0,Letter_Count=0; for(inti=0;i<132;i++) { if((Line[i]!='')&&(Line[i]!=0)&&(Line[i]!='\n'))Letter_Count++; else{ if(Letter_Count!=0){ if(Letter_Count%2){ OddWords++;Word_Count++; Letter_Count=0; } else{ EvenWords++; Word_Count++; Letter_Count=0; } } if(Line[i]==0)break; } } return(Word_Count*10000+OddWords*100+EvenWords);}DWORDWINAPICountWords(LPVOIDarg){BOOLbDone=FALSE;charinLine[132];intlCount=0; while(!bDone) {WaitForSingleObject(hSem1,INFINITE);//進(jìn)?bDone=(GetNextLine(fd,inLine)==EOF); ReleaseSemaphore(hSem1,1,NULL);//出? if(!bDone){ lCount=GetWordAndLetterCount(inLine); WaitForSingleObject(hSem2,INFINITE);//進(jìn)?TotalWords+=lCount/10000; TotalOddWords+=(lCount%10000)/100; TotalEvenWords+=lCount%100; ReleaseSemaphore(hSem2,1,NULL);//出?}} re