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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 han-
     dlers is called at	a different place in the fork(2) sequence.  The
     prepare handler is	called in the parent process before the	fork happens,
     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 regis-
     ter 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	han-
			dlers.

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) func-
     tions.  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

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | CAVEATS | BUGS

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