pthread_atfork(3) [osx man page]

PTHREAD_ATFORK(3)					   BSD Library Functions Manual 					 PTHREAD_ATFORK(3)

NAME

     pthread_atfork -- register handlers to be called before and after fork()

SYNOPSIS

     #include <pthread.h>

     int
     pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));

DESCRIPTION

     The pthread_atfork() function is used to register functions to be called before and after fork().	The prepare handler is called before
     fork(), while the parent and child handlers are called after fork() in the parent and child process respectively.	The prepare handlers are
     called in reverse order of their registration, while parent and child handlers are called in the order in which they were registered.  Any of
     the handlers may be NULL.

     Important: only async-signal-safe functions are allowed on the child side of fork().  See sigaction(2) for details.

RETURN VALUES

     If successful, the pthread_atfork() function will return zero; otherwise an error number will be returned to indicate the error.

ERRORS

     pthread_atfork() will fail if:

     [ENOMEM]		The system lacked the necessary resources to add another handler to the list.

SEE ALSO

     fork(2)

STANDARDS

     pthread_atfork() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').

BSD
								  August 12, 2004							       BSD

PTHREAD_ATFORK(3)					   BSD Library Functions Manual 					 PTHREAD_ATFORK(3)

NAME

     pthread_atfork -- register handlers to be called when process forks

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <pthread.h>

     int
     pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));

DESCRIPTION

     The pthread_atfork() function registers the provided handler functions to be called when the fork(2) function is called.  Each of the three
     handlers is called at a different place in the fork(2) sequence.  The prepare handler is called in the parent process before the fork hap-
     pens, the parent handler is called in the parent process after the fork has happened, and the child handler is called in the child process
     after the fork has happened.  The parent and child handlers are called in the order in which they were registered, while the prepare handlers
     are called in reverse of the order in which they were registered.

     Any of the handlers given may be NULL.

     The intended use of pthread_atfork() is to provide a consistent state to a child process from a multithreaded parent process where locks may
     be acquired and released asynchronously with respect to the fork(2) call.	Each subsystem with locks that are used in a child process should
     register handlers with pthread_atfork() that acquires those locks in the prepare handler and releases them in the parent handler.

RETURN VALUES

     The pthread_atfork() function returns 0 on success and an error number on failure.

ERRORS

     The following error code may be returned:

     [ENOMEM]		Insufficient memory exists to register the fork handlers.

SEE ALSO

     fork(2)

STANDARDS

     The pthread_atfork() function conforms to IEEE Std 1003.1c-1995 (``POSIX.1'').

HISTORY

     The pthread_atfork() function first appeared in NetBSD 2.0.

CAVEATS

     After calling fork(2) from a multithreaded process, it is only safe to call async-signal-safe functions until calling one of the exec(3)
     functions.  The pthread_*() functions are not async-signal-safe, so it is not safe to use such functions in the child handler.

BUGS

     There is no way to unregister a handler registered with pthread_atfork().

BSD
								 February 12, 2003							       BSD