http://java.icmc.usp.br/resources/books/ibm_pthreads/users-16.htm
pthread_detach()--Detach a Thread
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Syntax #include <pthread.h>
int pthread_detach(pthread_t thread);
Threadsafe: Yes
Signal Safe: No
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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