Description:
------------
PHP does not free the memory it's using during and after a request when using apache2handler SAPI. apache2filter SAPI works fine.

The memory it's using is however reused, but if I would send 500MB data and only have 256MB RAM, the OOM killer would start killing processes and apache when there are no more processes to kill (depending on OOM killer used).

Reproduce code:
---------------
<?php
$string = '';
for ($i = 0; $i < 1024; $i++)
   $string .= 'A';

for ($i = 0; $i < (1024 * 200); $i++) {
   echo $string;
   flush();
}
?>

Expected result:
----------------
Low memory usage

Actual result:
--------------
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 8434 nobody    25   0  284m 238m  52m S  0.0 31.6   0:25.14 httpd