pcntl_signal function not being hit and CTRL+C doe

Question

I have a simple PHP script that I want to run from the terminal, and be able to process signal codes. The script creates a TCP server and processes connections. Not sure why, but I can't get signal processing to work:

<?php
declare(ticks = 1);

// Register shutdown command.
pcntl_signal(SIGINT, function ($sig) {
  echo 'Exiting with signal: ' . $sig;
  global $sock;
  global $client;
  socket_close($sock);
  socket_close($client);
  exit(1);
});

$address = '127.0.0.1';
$port = 1234;

$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($sock, $address, $port) or die('Could not bind to address.');
socket_listen($sock);

while (TRUE) {
  $client = socket_accept($sock);
  if ($client) {
    $input = socket_read($client, 1024000);
    socket_write($client, var_export($input, TRUE));
    socket_write($client, 'End of data transmission.');
    socket_close($client);
  }
  usleep(100);
}

CTRL+C does not kill the application or hit the function.
If I remove the pcntl_signal functions, CTRL+C kills the program as expected.

Based on the research I've done, this setup should work. I've tried it in PHP 5.5 and 5.6... Cannot get to work as intended.

Answer 1

Problem

The problem is that you are using socket_read() which performs blocking IO. PHP isn't able to process signals if it hangs in a blocking IO operation.

Solution

Use non blocking IO to read data from the socket. You can use the function socket_select() with a timeout in a loop to make sure a read wouldn't block.