(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)
pcntl_waitpid — Waits on or returns the status of a forked child
Description
pcntl_waitpid(
int $process_id,
int &$status,
int $flags = 0,
array
&$resource_usage = []
): int
If a child as requested by process_id 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
process_id The value of process_id can be one of the following:
possible values for
process_id
< -1
| wait for any child process whose process group ID is equal to the absolute value of process_id.
|
-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 process_id.
|
Note:
Specifying -1 as the process_id is equivalent to the functionality pcntl_wait() provides (minus flags).
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().
flags The value of flags is the value of zero or more of the following two global constants OR'ed together:
possible values for flags
WNOHANG
| 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
saguto dot l7cc at gmail
dot com ¶
14 years ago
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.
fx4084 at gmail dot com ¶
7 years ago
$childs = array();// Fork some process.
for($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[$key]);
}sleep(1);
}
?>
renmengyang567 at gmail dot com ¶
3 years ago
declare(ticks = 1);
function zp_handler($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);
}
}
}
?>
