多线程抢票（互斥锁 条件变量）

参考 极客时间:趣谈Linux操作系统

多线程执行

#include<pthread.h>
#include<stdio.h>
#include<stdlib.h>

#define NUM_OF_TASKS 5
	
void *downloadfile(void *filename){
	printf("I am downloading thr file %s!\n)",(char*)filename);
	sleep(10);
	long downloadtime = rand()%100;
	printf("I am finish downloading the file within %d minutes!\n",downloadtime);
	pthread_exit((void*)downloadtime);
}

int main(int argc,char* argv[]){
	char files[NUM_OF_TASKS][20]={"file1.av1","file2.rmvb","file3.mp4","file4.wmv","file5.flv"};
	pthread_t threads[NUM_OF_TASKS];
	int rc;
	int t;
	int downloadtime;
	
	pthread_attr_t thread_attr;
	pthread_attr_init(&thread_attr);
	pthread_attr_setdetachstate(&thread_attr,PTHREAD_CREATE_JOINABLE);
	
	for(t=0;t<NUM_OF_TASKS;t++){
	 printf("ctreating thread %d,please help me to download %s\n",t,files[t]);
		rc=pthread_create(&threads[t],&thread_attr,downloadfile,(void*)files[t]);
		if(rc){
		 printf("ERROR;return code from pthread_create() is %d\n",rc);
		 exit(-1);
		}
	}
	pthread_attr_destory(&thread_attr);
	for(t=0;t<NUM_OF_TASKS;t++){
	 pthread_join(threads[t],(void**)&downloadtime);
	 printf("Thread %d downloads the file %s in %d minutes.\n",t,files[t],downloadtime);
	}
	
	pthread_exit(NULL);
}
	

互斥锁多线程执行

#include<pthread.h>
#include<stdio.h>
#include<stdlib.h>

#define NUM_OF_TASKS 5

int money_of_tom = 100;
int money_of_jerry = 100;

pthread_mutex_t g_money_lock;

void *transfer(void* notused){
	pthread_t tid=pthread_self();
	printf("Thread %u is transfering money!\n",(unsigned int)tid);
	pthread_mutex_lock(&g_money_lock);
	sleep(rand()%10);
	money_of_tom+=10;
	sleep(rand()%10);
	money_of_jerry-=10;
	pthread_mutex_unlock(&g_money_lock);
	printf("Thread %u finish transfering money!\n",(unsigned int)tid);
	pthread_exit((void*)0);
}

int main(int argc,char* argv[]){
	pthread_t threads[NUM_OF_TASKS];
	int rc;
	int t;
	pthread_mutex_init(&g_money_lock,NULL);
	for(t=0;t<NUM_OF_TASKS;t++){
	 rc=pthread_create(&threads[t],NULL,transfer,NULL);
	 if(rc){
	  printf("ERROR;return code from pthread_create() is %d\n",rc);
	  exit(-1);
	 }
	}
	for(t=0;t<100;t++){
		pthread_mutex_lock(&g_money_lock);
		printf("money_of_tom+money_of_jerry = %d\n",money_of_tom+money_of_jerry);
		pthread_mutex_unlock(&g_money_lock);
		pthread_exit(NULL);
	}
}

加入环境变量和互斥锁的多线程执行

#include<pthread.h>
#include<stdio.h>
#include<stdlib.h>

#define NUM_OF_TASKS 3
#define MAX_TASK_QUEUE 11
	
char tasklist[MAX_TASK_QUEUE]="ABCDEFGHIJ";
int head=0;
int tail=0;

int quit=0;

pthread_mutex_t g_task_lock;
pthread_cond_t g_task_cv;


void* coder(void *notused){
	pthread_t tid=pthread_self();
	while(!quit){
		pthread_mutex_lock(&g_task_lock);
		while(head==tail){
		if(quit){
			pthread_mutex_unlock(&g_task_lock);
			pthread_exit((void*)0);
		 }
			printf("No task now ! Thread %u is grabing the task!\n",(unsigned int)tid);
		}
		char task=tasklist[head++];
		pthread_mutex_unlock(&g_task_lock);
		printf("Thread %u has a task %c now!\n",(unsigned int)tid,task);
		
		printf("Thread %u finish the task %c!\n",(unsigned int)tid,task);
	}
	pthread_exit((void*)0);
}




int main(int argc,char* argv[]){
	pthread_t threads[NUM_OF_TASKS];
	int rc;
	int t;
	
	pthread_mutex_init(&g_task_lock,NULL);
	pthread_cond_init(&g_task_cv,NULL);
	
	for(t=0;t<NUM_OF_TASKS;t++){
	 rc=pthread_create(&threads[t],NULL,coder,NULL);
	 if(rc){
	  printf("ERROR;return code from pthread_create() is %d \n",rc);
	  exit(-1);
	 }
	}
	
	
	for(t=1;t<=4;t++){
	pthread_mutex_lock(&g_task_lock);
	tail+=t;
	printf("I am boss,I assigned %d tasks,I notify all coders!\n",t);
	pthread_cond_broadcast(&g_task_cv);
	pthread_mutex_unlock(&g_task_lock);
	
	}
	
	
	
	
	 
	
	pthread_mutex_lock(&g_task_lock);
	quit=1;
	pthread_cond_broadcast(&g_task_cv);
	pthread_mutex_unlock(&g_task_lock);
	
	pthread_mutex_destroy(&g_task_lock);
	pthread_cond_destroy(&g_task_cv);
	pthread_exit(NULL);
	

}