Professional Multicore Programming: Design and Implementation for C++ Developers

Name

NAME

pthread_atfork — register fork handlers

SYNOPSIS

THR #include <pthread.h>

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

DESCRIPTION

The pthread_atfork() function shall declare fork handlers to be called before and after fork(), in the context of the thread that called fork(). The prepare fork handler shall be called before fork() processing commences. The parent fork handle shall be called after fork() processing completes in the parent process. The child fork handler shall be called after fork() processing completes in the child process. If no handling is desired at one or more of these three points, the corresponding fork handler address(es) may be set to NULL.

The order of calls to pthread_atfork() is significant. The parent and child fork handlers shall be called in the order in which they were established by calls to pthread_atfork(). The prepare fork handlers shall be called in the opposite order.

RETURN VALUE

Upon successful completion, pthread_atfork() shall return a value of zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_atfork() function shall fail if:

[ENOMEM]

Insufficient table space exists to record the fork handler addresses.

The pthread_atfork() function shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

There are at least two serious problems with the semantics of fork() in a multi-threaded program. One problem has to do with state (for example, memory) ...