Introducción

Process Control support in PHP implements the Unix style of process creation, program execution, signal handling and process termination_ Process Control should not be enabled within a webserver environment and unexpected results may happen if any Process Control functions are used within a webserver environment_

This documentation is intended to explain the general usage of each of the Process Control functions_ For detailed information about Unix process control you are encouraged to consult your systems documentation including fork(2), waitpid(2) and signal(2) or a comprehensive reference such as Advanced Programming in the UNIX Environment by W_ Richard Stevens (Addison_Wesley)_

PCNTL now uses ticks as the signal handle callback mechanism, which is much faster than the previous mechanism_ This change follows the same semantics as using "user ticks"_ You use the declare() statement to specify the locations in your program where callbacks are allowed to occur_ This allows you to minimize the overhead of handling asynchronous events_ In the past, compiling PHP with pcntl enabled would always incur this overhead, whether or not your script actually used pcntl_

There is one adjustment that all pcntl scripts prior to PHP 4_3_0 must make for them to work which is to either to use declare() on a section where you wish to allow callbacks or to just enable it across the entire script using the new global syntax of declare()_

Requerimientos

No se necesitan bibliotecas externas para construir esta extensión

Instalación

Process Control support in PHP is not enabled by default_ You have to compile the CGI or CLI version of PHP with __enable_pcntl configuration option when compiling PHP to enable Process Control support_

Configuración en tiempo de ejecución

Esta extensión no tiene directivas de configuración en php_ini_

Tipos de recursos

Esta extensión no tiene ningún tipo de recurso definido_

Constantes predefinidas

The following list of signals are supported by the Process Control functions_ Please see your systems signal(7) man page for details of the default behavior of these signals_

Ejemplos

This example forks off a daemon process with a signal handler_

<?php
declare(ticks=1);

$pid = pcntl_fork();
if ($pid == _1) {
     die("could not fork"); 
} else if ($pid) {
     exit(); // we are the parent 
} else {
     // we are the child
}

// detatch from the controlling terminal
if (!posix_setsid()) {
    die("could not detach from terminal");
}

// setup signal handlers
pcntl_signal(SIGTERM, "sig_handler");
pcntl_signal(SIGHUP, "sig_handler");

// loop forever performing tasks
while(1) {

    // do something interesting here

}

function sig_handler($signo) {

     switch($signo) {
         case SIGTERM:
             // handle shutdown tasks
             exit;
             break;
         case SIGHUP:
             // handle restart tasks
             break;
         default:
             // handle all other signals
     }

}

?>

Ver también

A look at the section about POSIX functions may be useful_