pthread_tryjoin_np

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



NAME
       pthread_tryjoin_np, pthread_timedjoin_np - try to join with a terminated
       thread

SYNOPSIS
       #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);

       Compile and link with -pthread.

DESCRIPTION
       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, measured against the CLOCK_REALTIME clock.  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 */
           };

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

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

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

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

       ETIMEDOUT
              The call timed out before thread terminated.

       EINVAL abstime value is invalid (tv_sec is less than 0 or tv_nsec is
              greater than 1e9).

       pthread_timedjoin_np() never returns the error EINTR.

VERSIONS
       These functions first appeared in glibc in version 2.3.3.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                     Attribute     Value   │
       ├──────────────────────────────────────────────┼───────────────┼─────────┤
       │pthread_tryjoin_np(), pthread_timedjoin_np()  │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────┴───────────────┴─────────┘

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

EXAMPLES
       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 */
           }

BUGS
       The pthread_timedjoin_np() function measures time by internally
       calculating a relative sleep interval that is then measured against the
       CLOCK_MONOTONIC clock instead of the CLOCK_REALTIME clock.  Consequently,
       the timeout is unaffected by discontinuous changes to the CLOCK_REALTIME
       clock.

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

COLOPHON
       This page is part of release 5.12 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux                              2021-03-22              PTHREAD_TRYJOIN_NP(3)