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Full Discussion: unable to use a function to crate a joinable thread
Top Forums Programming unable to use a function to crate a joinable thread Post 302518209 by sehang on Friday 29th of April 2011 12:02:13 AM
Old 04-29-2011
unable to use a function to crate a joinable thread
In my program, threads may be created when some events trigger. So I can't create threads on initialization.

Theremore,I write a createThread() function to create thread. However, it is blocking at first call and don't run anymore? why?

Code:
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void *BusyWork(void *t)
{
   int i = 0;
   long tid;
   double result=0.0;
   tid = (long)t;
   printf("Thread %ld starting...\n",tid);
   while ( 1 ) {
      result = result + sin(i) * tan(i);
      i++;
   }
   printf("Thread %ld done. Result = %e\n",tid, result);
   pthread_exit((void*) t);
}


void createThread () {
  int rc;
  void *status;
  pthread_attr_t attr;
  pthread_t thread;
  pthread_attr_init(&attr);
  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
  rc = pthread_create(&thread, &attr, BusyWork, (void *)0); 
  if (rc) {
    printf("ERROR; return code from pthread_create() is %d\n", rc);
    exit(-1);
   }
    pthread_attr_destroy(&attr);
    rc = pthread_join(thread, &status);
    if (rc) {
       printf("ERROR; return code from pthread_join() is %d\n", rc);
       exit(-1);
    }
    printf("Main: completed join with thread %d having a status of %ld\n",0,(long)status);
}

int main (int argc, char *argv[])
{
  createThread();  // <- Blocking here
  createThread();  
  printf("Main: program completed. Exiting.\n");
  pthread_exit(NULL);
}

Thanks for your help!
 

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LEARN ABOUT LINUX

pthread_attr_getdetachstate

PTHREAD_ATTR_SETDETACHSTATE(3)				     Linux Programmer's Manual				    PTHREAD_ATTR_SETDETACHSTATE(3)

NAME

       pthread_attr_setdetachstate, pthread_attr_getdetachstate - set/get detach state attribute in thread attributes object

SYNOPSIS

       #include <pthread.h>

       int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate);
       int pthread_attr_getdetachstate(pthread_attr_t *attr, int *detachstate);

       Compile and link with -pthread.

DESCRIPTION

       The pthread_attr_setdetachstate() function sets the detach state attribute of the thread attributes object referred to by attr to the value
       specified in detachstate.  The detach state attribute determines whether a thread created using the thread attributes object attr  will	be
       created in a joinable or a detached state.

       The following values may be specified in detachstate:

       PTHREAD_CREATE_DETACHED
	      Threads that are created using attr will be created in a detached state.

       PTHREAD_CREATE_JOINABLE
	      Threads that are created using attr will be created in a joinable state.

       The default setting of the detach state attribute in a newly initialized thread attributes object is PTHREAD_CREATE_JOINABLE.

       The  pthread_attr_getdetachstate()  returns  the  detach  state	attribute of the thread attributes object attr in the buffer pointed to by
       detachstate.

RETURN VALUE

       On success, these functions return 0; on error, they return a nonzero error number.

ERRORS

       pthread_attr_setdetachstate(3) can fail with the following error:

       EINVAL An invalid value was specified in detachstate.

CONFORMING TO

       POSIX.1-2001.

NOTES

       See pthread_create(3) for more details on detached and joinable threads.

       A thread that is created in a joinable state should eventually either be joined using pthread_join(3) or detached using	pthread_detach(3);
       see pthread_create(3).

       It  is  an  error  to  specify  the  thread  ID	of  a  thread that was created in a detached state in a later call to pthread_detach(3) or
       pthread_join(3).

EXAMPLE

       See pthread_attr_init(3).

SEE ALSO

       pthread_attr_init(3), pthread_create(3), pthread_detach(3), pthread_join(3), pthreads(7)

COLOPHON

       This page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2010-02-03					    PTHREAD_ATTR_SETDETACHSTATE(3)
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