pthread_tryjoin_np, pthread_timedjoin_np — try to join with a terminated thread


#define _GNU_SOURCE              /* See feature_test_macros(7) */
#include <pthread.h>
int pthread_tryjoin_np( pthread_t thread,
  void **retval);
int pthread_timedjoin_np( pthread_t thread,
  void **retval,
  const struct timespec *abstime);
[Note] Note

Compile and link with −pthread.


These functions operate in the same way as pthread_join(3), except for the differences described on this page.

The pthread_tryjoin_np() function performs a nonblocking join with the thread thread, returning the exit status of the thread in *retval. If thread has not yet terminated, then instead of blocking, as is done by pthread_join(3), the call returns an error.

The pthread_timedjoin_np() function performs a join-with-timeout. If thread has not yet terminated, then the call blocks until a maximum time, specified in abstime. If the timeout expires before thread terminates, the call returns an error. The abstime argument is a structure of the following form, specifying an absolute time measured since the Epoch (see time(2)):

struct timespec {
  time_t   tv_sec;
/* seconds */
  long   tv_nsec;
/* nanoseconds */


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


These functions can fail with the same errors as pthread_join(3). pthread_tryjoin_np() can in addition fail with the following error:


thread had not yet terminated at the time of the call.

pthread_timedjoin_np() can in addition fail with the following error:


The call timed out before thread terminated.

pthread_timedjoin_np() never returns the error EINTR.


These functions first appeared in glibc in version 2.3.3.


These functions are nonstandard GNU extensions; hence the suffix "_np" (nonportable) in the names.


The following code waits to join for up to 5 seconds:

    struct timespec ts;
    int s;


    if (clock_gettime(CLOCK_REALTIME, &ts) == −1) {
        /* Handle error */

    ts.tv_sec += 5;

    s = pthread_timedjoin_np(thread, NULL, &ts);
    if (s != 0) {
        /* Handle error */


clock_gettime(2), pthread_exit(3), pthread_join(3), pthreads(7)


This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at−pages/.

  Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.