PHP Daemon/worker environment

Question

Problem: I want to implement several php-worker processes who are listening on a MQ-server queue for asynchronous jobs. The problem now is that simply running this processes as daemons on a server doesn't really give me any level of control over the instances (Load, Status, locked up)...except maybe for dumping ps -aux. Because of that I'm looking for a runtime environment of some kind that lets me monitor and control the instances, either on system (process) level or on a higher layer (some kind of Java-style appserver)

Any pointers?

Answer 1

Here's some code that may be useful.

<?
define('WANT_PROCESSORS', 5);
define('PROCESSOR_EXECUTABLE', '/path/to/your/processor');
set_time_limit(0);
$cycles = 0;
$run = true;
$reload = false;
declare(ticks = 30);

function signal_handler($signal) {
    switch($signal) {
    case SIGTERM :
        global $run;
        $run = false;
        break;
    case SIGHUP  :
        global $reload;
        $reload = true;
        break;
    }   
}

pcntl_signal(SIGTERM, 'signal_handler');
pcntl_signal(SIGHUP, 'signal_handler');

function spawn_processor() {
    $pid = pcntl_fork();
    if($pid) {
        global $processors;
        $processors[] = $pid;
    } else {
        if(posix_setsid() == -1)
            die("Forked process could not detach from terminal\n");
        fclose(stdin);
        fclose(stdout);
        fclose(stderr);
        pcntl_exec(PROCESSOR_EXECUTABLE);
        die('Failed to fork ' . PROCESSOR_EXECUTABLE . "\n");
    }
}

function spawn_processors() {
    global $processors;
    if($processors)
        kill_processors();
    $processors = array();
    for($ix = 0; $ix < WANT_PROCESSORS; $ix++)
        spawn_processor();
}

function kill_processors() {
    global $processors;
    foreach($processors as $processor)
        posix_kill($processor, SIGTERM);
    foreach($processors as $processor)
        pcntl_waitpid($processor);
    unset($processors);
}

function check_processors() {
    global $processors;
    $valid = array();
    foreach($processors as $processor) {
        pcntl_waitpid($processor, $status, WNOHANG);
        if(posix_getsid($processor))
            $valid[] = $processor;
    }
    $processors = $valid;
    if(count($processors) > WANT_PROCESSORS) {
        for($ix = count($processors) - 1; $ix >= WANT_PROCESSORS; $ix--)
            posix_kill($processors[$ix], SIGTERM);
        for($ix = count($processors) - 1; $ix >= WANT_PROCESSORS; $ix--)
            pcntl_waitpid($processors[$ix]);
    } elseif(count($processors) < WANT_PROCESSORS) {
        for($ix = count($processors); $ix < WANT_PROCESSORS; $ix++)
            spawn_processor();
    }
}

spawn_processors();

while($run) {
    $cycles++;
    if($reload) {
        $reload = false;
        kill_processors();
        spawn_processors();
    } else {
        check_processors();
    }
    usleep(150000);
}
kill_processors();
pcntl_wait();
?>

Answer 2

Do you actually need it to be continuously running?

If you only want to spawn new process on request, you can register it as a service in xinetd.

Answer 3

It sounds like you already have a MQ up and running on a *nix system and just want a way to manage workers.

A very simple way to do so is to use GNU screen. To start 10 workers you can use:

#!/bin/sh
for x in `seq 1 10` ; do
screen -dmS worker_$x php /path/to/script.php worker$x
end

This will start 10 workers in the background using screens named worker_1,2,3 and so on.

You can reattach to the screens by running screen -r worker_ and list the running workers by using screen -list.

For more info this guide may be of help: http://www.kuro5hin.org/story/2004/3/9/16838/14935

Also try:

• screen --help
• man screen
• or google.

For production servers I would normally recommend using the normal system startup scripts, but I have been running screen commands from the startup scripts for years with no problems.

Answer 4

a pcntl plugin type server daemon for PHP

http://dev.pedemont.com/sonic/