Two files used to try and test for weakness of openssl_random_pseudo_bytes().

example_run.txt

$ php test.php 1>log 
New process: 10500 16:44:52
New process: 11000 16:44:55
New process: 11500 10:00:02
New process: 12000 10:00:02
New process: 12500 10:00:02
New process: 13000 16:45:06
New process: 13500 10:00:02
New process: 14000 10:00:02
[... snipped for brevity ...]
New process: 5500 10:00:02
New process: 6000 10:00:02
New process: 6500 16:47:24
New process: 7000 10:00:02
New process: 7500 10:00:02
New process: 8000 10:00:02
New process: 8500 16:47:35
New process: 9000 10:00:02
New process: 9500 10:00:02
New process: 10000 10:00:02
New process: 10500 16:47:46
New process: 11000 10:00:02 
New process: 11500 10:00:02 // Now it's wrapped the pid counter and ran with the same time setting, you can kill the test.php script
New process: 12000 16:47:54

$ cat log | sort | uniq -d | head
00052b6a
0019930d
001ce092
001f9a30
0034a3db
00361f03
003ade92
003e0f7f
004039d8
0044c346

$ cat log | grep 00052b6a
00052b6a
00052b6a

test.php

<?php

// Explicitly initialize the PRNG in the parent process.  
openssl_random_pseudo_bytes(4);

for ($i = 0; $i < (65535 * 10); $i++)
{
	$pid = pcntl_fork();
	if ($pid == -1) {
    		die('could not fork');
	} else if ($pid) {
     		// we are the parent
		if (($pid % 500) == 0)
		{
			fwrite(STDERR,"New process: $pid " . date('H:i:s') . "\n");
			`sudo date -s "2016-03-24 10:00:00"`; // reset the time 
		}

     		pcntl_wait($status); //Protect against Zombie children

	} else {
		$pid = getmypid();
	
		for ($j = 0; $j < 10; $j++)
			echo bin2hex(openssl_random_pseudo_bytes(4)), "\n";

		 	
		 exit(0);
	}
}

wreck-pids.php

<?php

// Help test.php wrap the pid counter quicker by creating a lot of processes
for($i=0;$i<655350; $i++)
{
	$pid = pcntl_fork();
	
	if ($pid == -1) 
	{
     		die('could not fork');
	} 
	else if ($pid) 
	{
     		pcntl_wait($status); 
	} 
	else 
	{
		exit(0);
	}
}