stream_select() not working on regular files?

Hi,
I'm trying to implement something similar to "tail -f" in php but I'm 
running into a problem.
The issue occurs when I've reached the end of the file. From here I 
basically have to loop until new lines get appended to the file but I would 
like to respond immediately when then happens. There are three options that 
I can see:

1. Busy-loop
pro: I can process new lines immediately
contra: Excessivley CPU intensive => not a real option

2. add a sleep(1) to the loop
pro: No longer kills the CPU
contra: I might get a 1 second delay until I can process new lines

3. stream_select(array($fh),null,null,1)
pro: sleeps for one second but returns earlier if new data arrives
contra: doesn't seem to work in files?

Method 3 is the preferable one but doesn't seem to work:

$fh = fopen("testfile","r");
$r = array($fh);
while( ($n = stream_select($r,$w=null,$e=null,1)) == 1 ) {
     echo fgets($fh);
}

This program will loop forever because stream_select() will always return 1 
even at the end of the file.

Is there any other way to accomplish this?

Regards,
   Dennis