pcntl_waitpid
(PHP 4 >= 4.1.0, PHP 5)
pcntl_waitpid — Waits on or returns the status of a forked child
Description
$pid
, int &$status
[, int $options = 0
] )
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.
Parameters
-
pid -
The value of
pidcan 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.Note:
Specifying -1 as the
pidis equivalent to the functionality pcntl_wait() provides (minusoptions). -
status -
pcntl_waitpid() will store status information in the
statusparameter 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
optionsis the value of zero or more of the following two global constants OR'ed together:possible values for optionsWNOHANG return immediately if no child has exited. WUNTRACED return for children which are stopped, and whose status has not been reported.
Return Values
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
See Also
- pcntl_fork() - Forks the currently running process
- pcntl_signal() - Installs a signal handler
- pcntl_wifexited() - Checks if status code represents a normal exit
- pcntl_wifstopped() - Checks whether the child process is currently stopped
- pcntl_wifsignaled() - Checks whether the status code represents a termination due to a signal
- pcntl_wexitstatus() - Returns the return code of a terminated child
- pcntl_wtermsig() - Returns the signal which caused the child to terminate
- pcntl_wstopsig() - Returns the signal which caused the child to stop
- 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);
}
}
}
?>