завершение потока (thread termination)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
pthread_exit — thread termination
Синопсис (Synopsis)
#include <pthread.h>
void pthread_exit(void *value_ptr);
Описание (Description)
The pthread_exit() function shall terminate the calling thread
and make the value value_ptr available to any successful join
with the terminating thread. Any cancellation cleanup handlers
that have been pushed and not yet popped shall be popped in the
reverse order that they were pushed and then executed. After all
cancellation cleanup handlers have been executed, if the thread
has any thread-specific data, appropriate destructor functions
shall be called in an unspecified order. Thread termination does
not release any application visible process resources, including,
but not limited to, mutexes and file descriptors, nor does it
perform any process-level cleanup actions, including, but not
limited to, calling any atexit() routines that may exist.
An implicit call to pthread_exit() is made when a thread other
than the thread in which main() was first invoked returns from
the start routine that was used to create it. The function's
return value shall serve as the thread's exit status.
The behavior of pthread_exit() is undefined if called from a
cancellation cleanup handler or destructor function that was
invoked as a result of either an implicit or explicit call to
pthread_exit().
After a thread has terminated, the result of access to local
(auto) variables of the thread is undefined. Thus, references to
local variables of the exiting thread should not be used for the
pthread_exit() value_ptr parameter value.
The process shall exit with an exit status of 0 after the last
thread has been terminated. The behavior shall be as if the
implementation called exit() with a zero argument at thread
termination time.
Возвращаемое значение (Return value)
The pthread_exit() function cannot return to its caller.
Ошибки (Error)
No errors are defined.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
The normal mechanism by which a thread terminates is to return
from the routine that was specified in the pthread_create() call
that started it. The pthread_exit() function provides the
capability for a thread to terminate without requiring a return
from the start routine of that thread, thereby providing a
function analogous to exit().
Regardless of the method of thread termination, any cancellation
cleanup handlers that have been pushed and not yet popped are
executed, and the destructors for any existing thread-specific
data are executed. This volume of POSIX.1‐2017 requires that
cancellation cleanup handlers be popped and called in order.
After all cancellation cleanup handlers have been executed,
thread-specific data destructors are called, in an unspecified
order, for each item of thread-specific data that exists in the
thread. This ordering is necessary because cancellation cleanup
handlers may rely on thread-specific data.
As the meaning of the status is determined by the application
(except when the thread has been canceled, in which case it is
PTHREAD_CANCELED), the implementation has no idea what an illegal
status value is, which is why no address error checking is done.
Будущие направления (Future directions)
None.
Смотри также (See also)
exit(3p), pthread_create(3p), pthread_join(3p)
The Base Definitions volume of POSIX.1‐2017, pthread.h(0p)
