threads6 线程脱离属性detach

最新推荐文章于 2022-11-11 09:11:08 发布

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最新推荐文章于 2022-11-11 09:11:08 发布

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分类专栏：语言-c-glibc-posix 文章标签： thread function join null linux

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本文通过一个具体的C语言示例程序，详细介绍了如何使用POSIX线程库（pthread）来创建和管理线程，包括线程的创建、设置属性、同步与等待等关键操作。

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//beginging linux programming ch12
[root@localhost ch12]# cat thread5.c 
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>

void *thread_function(void *arg);

char message[] = "Hello World";
int thread_finished = 0;
    int res;
int main() {
	int res;
	pthread_t a_thread;
	void *thread_result;
	pthread_attr_t thread_attr;

	res = pthread_attr_init(&thread_attr);
	if (res != 0) {
	perror("Attribute creation failed");
	exit(EXIT_FAILURE);
	}
	res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
	if (res != 0) {
	perror("Setting detached attribute failed");
	exit(EXIT_FAILURE);
	}


	res = pthread_create(&a_thread,NULL, thread_function, (void *)message);
	//&thread_attr

	if (res != 0) {
	perror("Thread creation failed");
	exit(EXIT_FAILURE);
	}


	(void)pthread_attr_destroy(&thread_attr);
	 res = pthread_join(a_thread, &thread_result);
	printf("Other thread finished, bye!\n");
	// pthread_exit(NULL);
	exit(0);
}

void *thread_function(void *arg) {

	printf("thread_function is running. Argument was %s\n", (char *)arg);
	sleep(1);
	printf("Second thread setting finished flag, and exiting now\n");
	thread_finished = 1;
	pthread_exit(NULL);
}
[root@localhost ch12]# make
cc -D_REENTRANT  -lpthread  thread5.c   -o thread5
[root@localhost ch12]# ./thread5
thread_function is running. Argument was Hello World
Second thread setting finished flag, and exiting now
Other thread finished, bye!
[root@localhost ch12]#

modify line31 shown below

	res = pthread_create(&a_thread,&thread_attr, thread_function, (void *)message);

then

[root@localhost ch12]# ./thread5
Other thread finished, bye!
[root@localhost ch12]#

可见
用NULL创建的子线程，主线程可用pthread_join使自己等待子线程结束(主线程阻塞在pthread_join的位置)
而用DETACH创建的子线程，主线程用pthread_join也不会使自己阻塞,而是一直执行