Description:
------------
I run three very active machines which all use dio to lock files on an NFS export.

Several times a day, one of the php instances randomly locks up and spins with 
100% CPU, and this will complete.

I've traced the issue down to dio_open - which, for some reason, sometimes causes 
the CPU to spin away and it never returns.



Test script:
---------------
Here's the code block that the issue occurs in. PLEASE NOTE:  This code works 99.9999% of the time - the issue, unfortunately, cannot be reliably reproduced.

$flags = O_RDONLY;
$locktype = F_RDLCK;
$locked = false;

while($locked === false)
{
	$this->handle = @dio_open($filename, $flags, 0777);	
	if ($this->handle===false) break;
	$res = @dio_fcntl($this->handle, F_SETLK, Array("type"=>$locktype));
	if ($res!=-1)
	{
		$locked = true;	
	}
	else
	{
		@dio_close($this->handle);
		$this->handle=false;	
		usleep(250000);
	}
}