c语言多线程pthread库概览

- pthread.h #man pthread

- pthread_t th; pthread_create(&th,NULL,a_func,NULL); #afunc :(void *)->(void*)

- main不等待线程的，主死线程也死

- pthread_join(th,NULL);等待线程th

 - 多线程跑时，不知道谁先走，线程可交叉执行

#include 
#include 
#include 

void* myfunc(void* args){
	for(int i=0;i<10;i++){
		printf("myfunc + hello world\n");
	}
	return NULL;
}
void* othfunc(void* args){
	for(int i = 1; i< 10;i++){
		printf("othfunc + %d\n",i);
	}
	return NULL;
}

int main(int argc,char** argv){
	pthread_t th;
	pthread_t th1;
	pthread_create(&th,NULL,myfunc,NULL);
	pthread_create(&th1,NULL,othfunc,NULL);
	pthread_join(th,NULL);
	pthread_join(th1,NULL);
	return 0;
}

#include 
#include 
#include 

void* myfunc(void* args){
	for(int i=0;i<10;i++){
		printf("myfunc + hello world\n");
	}
	return NULL;
}
void* othfunc(void* args){
	for(int i = 1; i< 10;i++){
		printf("othfunc + %d\n",i);
	}
	return NULL;
}

typedef struct {
	int first,second;
}Args;

void* cntfunc(void* args){
	int i, sum = 0;
	Args* two_args = (Args*) args;
	int first = two_args->first;
	int second = two_args->second;

	for(i = first;i

- 数据竞争时就要加锁

- pthread_mutex_t lock;

- pthread_mutex_init(&lock,NULL);

- 对代码段加锁

pthread_mutex_lock(&lock);

s++;

pthread_mutex_unlock(&lock);

 

#include 
#include 
#include 



pthread_mutex_t lock;
int s = 0;
void* myfunc(void* args){
	pthread_mutex_lock(&lock);
	int i = 0;
	for(;i<10000;i++){
		s++;
	}
	pthread_mutex_unlock(&lock);
	return NULL;
}

int main(int argc,char** argv){
	pthread_mutex_init(&lock,NULL);

	pthread_t th;
	pthread_t th1;
	pthread_create(&th,NULL,myfunc,NULL);
	pthread_create(&th1,NULL,myfunc,NULL);
	pthread_join(th,NULL);
	pthread_join(th1,NULL);
	printf("%d\n", s);

	return 0;
}

- it works,但是这好像没有用到多线程，因为一旦加上上面的锁，程序也只能按序执行

- gcc pth.c -lpthread -o main

- time ./main