pcntl_waitpid
(PHP 4 >= 4.0.7, PHP 5)
pcntl_waitpid — Waits on or returns the status of a forked child
Описание
Suspends execution of the current process until a child as specified by the pid argument has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling function.
If a child as requested by pid has already exited by the time of the call (a so-called "zombie" process), the function returns immediately. Any system resources used by the child are freed. Please see your system's waitpid(2) man page for specific details as to how waitpid works on your system.
Список параметров
- pid
-
The value of pid can be one of the following:
possible values for pid < -1 wait for any child process whose process group ID is equal to the absolute value of pid . -1 wait for any child process; this is the same behaviour that the wait function exhibits. 0 wait for any child process whose process group ID is equal to that of the calling process. > 0 wait for the child whose process ID is equal to the value of pid . Замечание: Specifying -1 as the pid is equivalent to the functionality pcntl_wait() provides (minus options ).
- status
-
pcntl_waitpid() will store status information in the status parameter which can be evaluated using the following functions: pcntl_wifexited(), pcntl_wifstopped(), pcntl_wifsignaled(), pcntl_wexitstatus(), pcntl_wtermsig() and pcntl_wstopsig().
- options
-
The value of options is the value of zero or more of the following two global constants OR'ed together:
possible values for options WNOHANG return immediately if no child has exited. WUNTRACED return for children which are stopped, and whose status has not been reported.
Возвращаемые значения
pcntl_waitpid() returns the process ID of the child which exited, -1 on error or zero if WNOHANG was used and no child was available
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для управления процессами программ
- Process Control
- pcntl_alarm
- pcntl_errno
- pcntl_exec
- pcntl_fork
- pcntl_get_last_error
- pcntl_getpriority
- pcntl_setpriority
- pcntl_signal_dispatch
- pcntl_signal
- pcntl_sigprocmask
- pcntl_sigtimedwait
- pcntl_sigwaitinfo
- pcntl_strerror
- pcntl_wait
- pcntl_waitpid
- pcntl_wexitstatus
- pcntl_wifexited
- pcntl_wifsignaled
- pcntl_wifstopped
- pcntl_wstopsig
- pcntl_wtermsig
Коментарии
please note, if you using configure option --enable-sigchild(Enable PHP's own SIGCHLD handler) when complie php(under linux 2.6.18-53.1.13.el5.centos.plus and php 5.2.5 as I know), pcntl_waitpid and pcntl_wait in php script would never return the child pid, because the build in handle get it first.<?php
$childs = array();
// Fork some process.
for($i = 0; $i < 10; $i++) {
$pid = pcntl_fork();
if($pid == -1)
die('Could not fork');
if ($pid) {
echo "parent \n";
$childs[] = $pid;
} else {
// Sleep $i+1 (s). The child process can get this parameters($i).
sleep($i+1);
// The child process needed to end the loop.
exit();
}
}
while(count($childs) > 0) {
foreach($childs as $key => $pid) {
$res = pcntl_waitpid($pid, $status, WNOHANG);
// If the process has already exited
if($res == -1 || $res > 0)
unset($childs[$key]);
}
sleep(1);
}
?>
<?php
declare(ticks = 1);
function zp_handler($signal) {
$id = pcntl_waitpid(-1, $status, WNOHANG);
if (pcntl_wifexited($status))
{
printf("Removed Chlid id: %d \n",$id);
printf("Chlid status: %d \n",pcntl_wexitstatus($status));
}
}
//pcntl_signal_dispatch();
pcntl_signal(SIGCHLD, "zp_handler");
//pcntl_signal_dispatch();
//
$pid = pcntl_fork();
if ($pid == 0)
{
print "#1 Hi, I'm child process".PHP_EOL;
sleep(3);
return 10;
}
else
{
print "#1parent process id:".$pid.PHP_EOL;
$pid = pcntl_fork();
if ($pid == 0)
{ print "#2 Hi, I'm child process".PHP_EOL;
sleep(10);
exit(20);
}
else
{
print "#2parent process id:".$pid.PHP_EOL;
for ($i=0; $i <10 ; $i++) {
print "wait..".PHP_EOL;
sleep(10);
}
}
}
?>