call pthread_join() or pthread_detach() for every thread

最新推荐文章于 2024-05-07 15:12:55 发布

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最新推荐文章于 2024-05-07 15:12:55 发布

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原文链接：http://www.cnblogs.com/cy163/archive/2008/08/17/1269923.html

本文详细介绍了pthread_detach()函数的功能及用法，包括如何通过此函数回收指定线程结束后的系统资源，以及如何避免因未正确回收线程导致的资源泄露问题。此外，还提供了一个示例程序，演示了如何使用pthread_detach()。

http://java.icmc.usp.br/resources/books/ibm_pthreads/users-16.htm

pthread_detach()--Detach a Thread

Syntax

#include <pthread.h>
            int pthread_detach(pthread_t thread);
            Threadsafe: Yes
            Signal Safe: No

The pthread_detach() function indicates that system resources for the specified thread should be reclaimed when the thread ends. If the thread is already ended, resources are reclaimed immediately. This routine does not cause the thread to end. After pthread_detach() has been issued, it is not valid to try to pthread_join() with the target thread.

Eventually, you should call pthread_join() or pthread_detach() for every thread that is created joinable (with a detachstate of PTHREAD_CREATE_JOINABLE) so that the system can reclaim all resources associated with the thread. Failure to join to or detach joinable threads will result in memory and other resource leaks until the process ends.

If thread doesn't represent a valid undetached thread, pthread_detach() will return ESRCH.

Parameters

thread (Input) Pthread handle to the target thread

Authorities and Locks

None.

Return Value

0 pthread_detach() was successful. value pthread_detach() was not successful. value is set to indicate the error condition.

Error Conditions

If pthread_detach() was not successful, the error condition returned usually indicates one of the following errors. Under some conditions, the value returned could indicate an error other than those listed here.

[EINVAL] The value specified for the argument is not correct. [ESRCH] No item could be found that matches the specified value

Related Information

The <pthread.h> header file. See Header files for Pthread functions
pthread_exit()--Terminate The Calling Thread
pthread_create()--Create a Thread
pthread_join()--Wait for and Detach a Thread

Example

#define _MULTI_THREADED
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include "check.h"
void *threadfunc(void *parm)
{
printf("Inside secondary thread\n");
return NULL;
}
int main(int argc, char **argv)
{
pthread_t             thread;
int                   rc=0;
printf("Enter Testcase - %s\n", argv[0]);
printf("Create thread using attributes that allow join or detach\n");
rc = pthread_create(&thread, NULL, threadfunc, NULL);
checkResults("pthread_create()\n", rc);
sleep(5);
printf("Detach the thread after it terminates\n");
rc = pthread_detach(thread);
checkResults("pthread_detach()\n", rc);
printf("Detach the thread again (expect ESRCH)\n");
rc = pthread_detach(thread);
if (rc != ESRCH) {
printf("Got an unexpected result! rc=%d\n",
rc);
exit(1);
}
printf("Second detach fails correctly\n");
/* sleep() isn't a very robust way to wait for the thread */
sleep(5);
printf("Main completed\n");
return 0;
}

Output

Enter Testcase - QP0WTEST/TPDET0
Create thread using attributes that allow join or detach
Inside secondary thread
Detach the thread after it terminates
Detach the thread again (expect ESRCH)
Second detach fails correctly
Main completed

转载于:https://www.cnblogs.com/cy163/archive/2008/08/17/1269923.html