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pthread_atfork

NAME

SYNOPSIS

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

DESCRIPTION

!pthread_atfork! registers handler functions to be called just before and just after a new process is created with !fork!(2). The |prepare| handler will be called from the parent process, just before the new process is created. The |parent| handler will be called from the parent process, just before !fork!(2) returns. The |child| handler will be called from the child process, just before !fork!(2) returns.

One or several of the three handlers |prepare|, |parent| and |child| can be given as !NULL!, meaning that no handler needs to be called at the corresponding point.

!pthread_atfork! can be called several times to install several sets of handlers. At !fork!(2) time, the |prepare| handlers are called in LIFO order (last added with !pthread_atfork!, first called before !fork!), while the |parent| and |child| handlers are called in FIFO order (first added, first called).

To understand the purpose of !pthread_atfork!, recall that !fork!(2) duplicates the whole memory space, including mutexes in their current locking state, but only the calling thread: other threads are not running in the child process. The mutexes are not usable after the !fork! and must be initialized with |pthread_mutex_init| in the child process. This is a limitation of the current implementation and might or might not be present in future versions.

RETURN VALUE

!pthread_atfork! returns 0 on success and a non-zero error code on error.

ERRORS

!ENOMEM!

insufficient memory available to register the handlers.

AUTHOR

SEE ALSO