I've been developping a daemon-script that runs in the background, after being spawned from the parent script.

i use an:

//  we are parent. spawn child and exit.
    $sock = fsockopen (getenv("SERVER_NAME"), 80);
    if(!$sock){
      echo "ERROR: $errstr ($errno)\n";
    } else {
      if(socket_set_blocking($sock, false)){
        fputs($sock, "GET ".getenv("REQUEST_URI")."?child=1 HTTP/1.1\n");
        fputs($sock, "Host: ".getenv("SERVER_NAME")." \n");
        fputs($sock, "Connection: close\n\n");
        fclose($sock);
    } else {
      echo "ERROR: blocking socket. execution halted.\n";
      exit();
    }
  }

to spawn the child process (fork is not supported on the system this script is developed for). this code essentially opens a non-blocking socket to itself, with the variable child=1, and exits. the child process is now running.

this child process starts with:

  set_time_limit (0);
  ignore_user_abort(true);

to be able to run "forever"...
after this it goes into an eternal while loop.

now, the problem is the following: if nothing happens within the loop (e.g. no output is produced, the script only checks and sleeps) the script halts (but doesn't die/exit) after exactly 300 seconds. the process still exists in the process list on the server.

if the script produces an non-fatal error within every 300 seconds, it continues running happily for hours and hours and hours.

i tried outputting a "boo" message using echo "boo"; every ten seconds, and that didn't seem to work. i tried flushing after echoing, that didn't work either. now i free a mysql-result that doesn't exist, and that DOES work!