create a thread from a returning function Post: 302192841

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Top Forums Programming create a thread from a returning function Post 302192841 by andryk on Thursday 8th of May 2008 03:11:54 AM

05-08-2008

Registered User

Quote:

Originally Posted by wolwy_pete

hi all,
my requirement is to create a thread by calling another function.
i.e i dont call pthread_create directly from main, but by calling another function (createThd - below ), from main.
Example:

Code:

void *thread_function(void *arg) {  /* thread function */
	int i;
	rc = pthread_detach(pthread_self());
	for ( ; ; )  {
		printf("Thread says hi!\n");
		sleep(1);
	}
	pthread_exit(NULL);
}

int main(void) {

	int i;
	i = createThd();  /* call to thread creating function */

	return (0);

}

int createThd()
{
	int rc = 0;
	pthread_t mythread;

	if ( pthread_create( &mythread, NULL, thread_function, NULL) ) {
		printf("error creating thread.");
		return(-1);
	}
	return 0;
}

this creates the thread but doesnt run it, thread terminates as soon as the function createThd() returns.
is there a way to overcome this problem.

any help is appreciated, thankx in advanced.
wolwy.

Hi,
You could wait on createThd() until thread_function() has done his job by means of pthread_cond_wait/pthread_cond_signal & mutexes, just like a parent process would wait (with wait/waitpid) for its child to terminate...

andryk

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pthread_detach

pthread_detach(3T)														pthread_detach(3T)

NAME

       pthread_detach() - mark a thread as detached to reclaim its resources when it terminates

SYNOPSIS

PARAMETERS

	      thread	Thread whose resources are to be reclaimed immediately when it terminates.

DESCRIPTION

       is  used  to detach the thread thread.  When thread terminates, its resources will automatically be reclaimed by the system.  If thread has
       already terminated, causes the resources of thread to be reclaimed by the system.

       does not cause thread to terminate.

       Once a detached thread has terminated, its resources, including the thread ID, may be reused by the system. The return status of a detached
       thread is lost when the thread terminates.

       Calling this function multiple times for the same thread results in undefined behavior.

RETURN VALUE

       Upon successful completion, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set).

ERRORS

       If any of the following occur, the function returns the corresponding error number:

	      [EINVAL]	     thread does not refer to a joinable thread.

	      [ESRCH]	     No thread could be found corresponding to thread.

AUTHOR

       was derived from the IEEE POSIX P1003.1c standard.

SEE ALSO

       pthread_create(3T), pthread_join(3T), wait(2).

STANDARDS CONFORMANCE

								  Pthread Library						pthread_detach(3T)

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