Question

I got trouble with web browsers buffering (not chaching).

I call this php script :

sleep(5);
echo '1st step';
echo (str_repeat(' ',256));
sleep(5);
echo '<br />';
echo '2nd step';

output buffer is disabled on php (we will confirm that later)

when calling this script with both Chromium 12 and Firefox 5
I got this result :

the ‘waiting’ animated circle (the grey one) runs during ~5sec
then the ‘transferring’ animated circle (the orange one) runs during ~5sec
and finally i have the whole result displayed.

My initial goal was, as you expect, to wait 5sec, then see “1st step” displayed,
wait 5sec again and then see “2nd step” displayed.

clues

• php or apache doesn’t buffer anything as the animated circle switch from
  ‘waiting’ to ‘recieving’ after 5sec (so the browser did recieve something
  from the “1st step” echo !)

  • I tried to set Firefox Cache size to 0 so the cache mechanism would be bypassed.. but still no working.

  • I read that some browser may wait until they recieve 256 bytes before they start display the content. That’s why i added “echo (str_repeat(‘ ‘,256))”.. but it doesn’t solve anything.

  • I also tried to set network.buffer.cache.count and network.buffer.cache.size options at 0 in firefox about:config, i don’t know if those option was rellated to my problem but it is still not working..

Any idea ?

Thanks,

Answer 1

Oh, I guess I need to make the answer an answer, not a comment, so you can accept it.

The HTML5 charset sniffing buffer size is 512 bytes. So the response needs to either have 512 bytes of padding or set a charset (via <meta> tag or HTTP header).