pthread_timedjoin_np(3) Linux Man Page

Name

pthread_tryjoin_np, pthread_timedjoin_np - try to join with a terminated thread

Library

POSIX threads library ( libpthread ", " -lpthread )

Synopsis

"#define(7)_GNU_SOURCE" "             /* See feature_test_macros */" #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 );

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 timespec(3) structure, specifying an absolute time measured since the Epoch (see time(2)).

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 .

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ pthread_tryjoin_np()pthread_timedjoin_np()

Interface	Attribute	Value
T}	Thread safety	MT-Safe

Standards

GNU; hence the suffix "_np" (nonportable) in the names.

History

glibc 2.3.3.

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 */
}

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