Description:
------------
Do you this think fflush() realy works? plese see following code

if you answer it's not a bug, please give me a example how to use fflush() correctly.

Reproduce code:
---------------
----before fflush----
<?php
$fp = fopen("1.txt", "w");
while(1)
{
   fwrite($fp, "a");
   sleep(1);
}
?>
----after fflush----
<?php
$fp1 = fopen("1.txt", "w");
$fp2 = fopen("2.txt", "w");
while(1)
{
   fwrite($fp1, "a");
   fflush($fp2);
   sleep(1);
}
?>

Expected result:
----------------
---before fflush---
no contents in file "1.txt" until it's buffer is full
---after  fflush---
"a  a  a  a....." in file "2.txt" immediately

Actual result:
--------------
---before fflush---
"a  a  a  a....." in file "1.txt" immediately
---after fflush---
empty in file "2.txt"