зарегистрировать обработчики вилок (register fork handlers)
Имя (Name)
pthread_atfork - register fork handlers
Синопсис (Synopsis)
#include <pthread.h>
int pthread_atfork(void (*prepare)(void), void (*parent)(void),
void (*child)(void));
Link with -pthread.
Описание (Description)
The pthread_atfork() function registers fork handlers that are to
be executed when fork(2) is called by this thread. The handlers
are executed in the context of the thread that calls fork(2).
Three kinds of handler can be registered:
* prepare specifies a handler that is executed before fork(2)
processing starts.
* parent specifies a handler that is executed in the parent
process after fork(2) processing completes.
* child specifies a handler that is executed in the child
process after fork(2) processing completes.
Any of the three arguments may be NULL if no handler is needed in
the corresponding phase of fork(2) processing.
Возвращаемое значение (Return value)
On success, pthread_atfork() returns zero. On error, it returns
an error number. pthread_atfork() may be called multiple times
by a thread, to register multiple handlers for each phase. The
handlers for each phase are called in a specified order: the
prepare handlers are called in reverse order of registration; the
parent and child handlers are called in the order of
registration.
Ошибки (Error)
ENOMEM Could not allocate memory to record the form handler
entry.
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
When fork(2) is called in a multithreaded process, only the
calling thread is duplicated in the child process. The original
intention of pthread_atfork() was to allow the calling thread to
be returned to a consistent state. For example, at the time of
the call to fork(2), other threads may have locked mutexes that
are visible in the user-space memory duplicated in the child.
Such mutexes would never be unlocked, since the threads that
placed the locks are not duplicated in the child. The intent of
pthread_atfork() was to provide a mechanism whereby the
application (or a library) could ensure that mutexes and other
process and thread state would be restored to a consistent state.
In practice, this task is generally too difficult to be
practicable.
After a fork(2) in a multithreaded process returns in the child,
the child should call only async-signal-safe functions (see
signal-safety(7)) until such time as it calls execve(2) to
execute a new program.
POSIX.1 specifies that pthread_atfork() shall not fail with the
error EINTR.
Смотри также (See also)
fork(2), atexit(3), pthreads(7)
