Manpages - pthread_tryjoin_np.3
Table of Contents
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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:
- EINVAL
- abstime value is invalid (tv_sec is less than 0 or tv_nsec is greater than 1e9).
- ETIMEDOUT
- The call timed out before thread terminated.
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.
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.
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 */ }
SEE ALSO
*clock_gettime*(2), *pthread_exit*(3), *pthread_join*(3), *pthreads*(7)
COLOPHON
This page is part of release 5.13 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/.