《Linux應(yīng)用實(shí)例教程》課件-講義28并發(fā)程序-父子進(jìn)程線程異步性

S10、并發(fā)程序-父子進(jìn)程線程異步性S10、并發(fā)程序-父子進(jìn)程線程異步性S10、并發(fā)程序-父子進(jìn)程線程異步性1、創(chuàng)建父子進(jìn)程，觀察父子進(jìn)程執(zhí)行的順序，了解進(jìn)程執(zhí)行的異步行為#include<stdio.h>#include<sys/types.h>#include<unistd.h>#include<stdlib.h>intmain(){pid_tpid;char*msg;S10、并發(fā)程序-父子進(jìn)程線程異步性

intk;printf("觀察父子進(jìn)程執(zhí)行的先后順序，了解調(diào)度算法的特征\n");pid=fork();switch(pid){case0:msg="子進(jìn)程在運(yùn)行";k=3;break;case-1:msg="進(jìn)程創(chuàng)建失敗";break;S10、并發(fā)程序-父子進(jìn)程線程異步性default:msg="父進(jìn)程在運(yùn)行";k=5;break;}while(k>0){puts(msg); sleep(1); k--; }exit(0);}S10、并發(fā)程序-父子進(jìn)程線程異步性編譯：gccparent-child-fork.c-oparent-child-fork運(yùn)行：./parent-child-forkS10、并發(fā)程序-父子進(jìn)程線程異步性2、創(chuàng)建主線程和子線程，觀察多線程執(zhí)行的順序，了解線程執(zhí)行的異步行為#include<stdio.h>#include<pthread.h>staticintrun=1;staticintretvalue;void*threadfunc(void*arg){ int*running=arg;

S10、并發(fā)程序-父子進(jìn)程線程異步性 printf("子線程初始化完畢，傳入?yún)?shù)為：%d\n",*running); while(*running) { printf("子線程正在運(yùn)行\(zhòng)n"); usleep(1); } printf("子線程退出\n"); retvalue=8; pthread_exit((void*)&retvalue);}S10、并發(fā)程序-父子進(jìn)程線程異步性intmain(){ pthread_tpt; intret=-1; inttimes=3; inti=0; int*ret_join=NULL; ret=pthread_create(&pt,NULL,(void*)threadfunc,&run); if(ret!=0) { printf("建立線程失敗\n"); return1; } printf("主線程創(chuàng)建子線程后在運(yùn)行...\n");S10、并發(fā)程序-父子進(jìn)程線程異步性 usleep(1); printf("主線程調(diào)用usleep(1)...\n"); for(;i<times;i++) { printf("主線程打印i=%d\n",i); usleep(1); } run=0; pthread_join(pt,(void*)&ret_join); printf("線程返回值為：%d\n",*ret_join); return0;}S10、并發(fā)程序-父子進(jìn)程線程異步性編譯：gccthread.c-othread-lpthread運(yùn)行：./threadS10、并發(fā)程序-父子進(jìn)程線程異步性3、多線程對(duì)共享變量的非互斥訪問(wèn)#include<stdio.h>#include<stdlib.h>#include<pthread.h>#include<unistd.h>#include<string.h>intnum=30,count=10;void*sub1(void*arg){inti=0,tmp;S10、并發(fā)程序-父子進(jìn)程線程異步性for(;i<count;i++){

tmp=num-1; usleep(13); num=tmp;

printf("線程1num減1后值為:%d\n",num);}return((void*)0);}void*sub2(void*arg){inti=0,tmp;for(;i<count;i++){

tmp=num-1; usleep(31);S10、并發(fā)程序-父子進(jìn)程線程異步性 num=tmp;printf("線程2num減1后值為:%d\n",num);}return((void*)0);}intmain(intargc,char**argv){pthread_ttid1,tid2;interr,i=0,tmp;void*tret;err=pthread_create(&tid1,NULL,sub1,NULL);if(err!=0){ printf("pthread_createerror:%s\n",strerror(err));exit(-1);

}S10、并發(fā)程序-父子進(jìn)程線程異步性err=pthread_create(&tid2,NULL,sub2,NULL);if(err!=0){ printf("pthread_createerror:%s\n",strerror(err));exit(-1);}for(;i<count;i++)

{

tmp=num-1; usleep(5);

num=tmp;printf("mainnum減1后值為:%d\n",num);}printf("兩個(gè)線程運(yùn)行結(jié)束\n");S10、并發(fā)程序-父子進(jìn)程線程異步性 err=pthread_join(tid1,&tret);if(err!=0){ printf("cannotjoinwiththread1:%s\n",strerror(err));exit(-1);}printf("thread1exitcode%d\n",(int)tret);err=pthread_join(tid2,&tret);if(err!=0){ printf("cannotjoinwiththread1:%s\n",strerror(err));exit(-1