popen()/proc_open() works parallel even in Windows.
Most often pitfall is "fread/stream_get_contents" without while loop. Once you try to fread() from running process it will block output for processes that run after it (cause of fread() waits until at least one byte arrives)
Add stream_select(). Closest analogy is "foreach with timeout but for streams", you pass few arrays to read and write and each call of stream_select() one or more streams will be selected. Function updates original arrays by reference, so dont forget to restore it to all streams before next call. Function gives them some time to read or write. If no content - control returns allowing us to retry cycle.
// sleep.php
set_error_handler(function ($severity, $error, $file, $line) {
throw new ErrorException($error, -1, $severity, $file, $line);
});
$sleep = $argv[ 1 ];
sleep($sleep);
echo $sleep . PHP_EOL;
exit(0);
// run.php
<?php
$procs = [];
$pipes = [];
$cmd = 'php %cd%/sleep.php';
$desc = [
0 => [ 'pipe', 'r' ],
1 => [ 'pipe', 'w' ],
2 => [ 'pipe', 'a' ],
];
for ( $i = 0; $i < 10; $i++ ) {
$iCmd = $cmd . ' ' . ( 10 - $i ); // add SLEEP argument to each command 10, 9, ... etc.
$proc = proc_open($iCmd, $desc, $pipes[ $i ], __DIR__);
$procs[ $i ] = $proc;
}
$stdins = array_column($pipes, 0);
$stdouts = array_column($pipes, 1);
$stderrs = array_column($pipes, 2);
while ( $procs ) {
foreach ( $procs as $i => $proc ) {
// @gzhegow > [OR] you can output while script is running (if child never finishes)
$read = [ $stdins[ $i ] ];
$write = [ $stdouts[ $i ], $stderrs[ $i ] ];
$except = [];
if (stream_select($read, $write, $except, $seconds = 0, $microseconds = 1000)) {
foreach ( $write as $stream ) {
echo stream_get_contents($stream);
}
}
$status = proc_get_status($proc);
if (false === $status[ 'running' ]) {
$status = proc_close($proc);
unset($procs[ $i ]);
echo 'STATUS: ' . $status . PHP_EOL;
}
// @gzhegow > [OR] you can output once command finishes
// $status = proc_get_status($proc);
//
// if (false === $status[ 'running' ]) {
// if ($content = stream_get_contents($stderrs[ $i ])) {
// echo '[ERROR]' . $content . PHP_EOL;
// }
//
// echo stream_get_contents($stdouts[ $i ]) . PHP_EOL;
//
// $status = proc_close($proc);
// unset($procs[ $i ]);
//
// echo 'STATUS: ' . $status . PHP_EOL;
// }
}
usleep(1); // give your computer one tick to decide what thread should be used
}
// ensure you receive 1,2,3... but you've just run it 10,9,8...
exit(0);
