[PHP-BUG] Bug #51523 [NEW]: Memory leak on fread()

From:             
Operating system: Linux
PHP version:      Irrelevant
Package:          Performance problem
Bug Type:         Bug
Bug description:Memory leak on fread()

Description:
------------
The problem is the fread() uses a normal amount of a memory. But there are
too many unallocated anonymous memory pages.
So if the file size >2G the script may cause eating up to 2G of RAM. But
the script's runtime memory is 5M.

The problem is occured even if:
$fp = fopen($file, "rb");
while(!feof($fp))
    fread($fp, 1024);
fclose($fp);

After that the memory isn't released so we have a garbadge in the memory.


Test script:
---------------
<?php

$file = "A.very.big.file.avi";
ob_start();
$fp = fopen($file, "wb");
if ($fp)
{
    while(!feof($fp))
    {
        echo(fread($fp, 1024));
        if (ob_get_length())
        {
            ob_flush();
            flush();
            ob_end_flush();
        }
    }
    fclose($fp);

    @ob_flush();
    @flush();
    @ob_end_flush();
    @ob_end_clean();
}
?>


Expected result:
----------------
The total amount of a memory usage should be at least <php script runtime
memory usage> + 1024 (+ some buffer (up to 8192)). But not almost all the
physical memory (0...unlimited)




-- 
Edit bug report at http://bugs.php.net/bug.php?id=51523&edit=1
-- 
Try a snapshot (PHP 5.2):            http://bugs.php.net/fix.php?id=51523&r=trysnapshot52
Try a snapshot (PHP 5.3):            http://bugs.php.net/fix.php?id=51523&r=trysnapshot53
Try a snapshot (PHP 6.0):            http://bugs.php.net/fix.php?id=51523&r=trysnapshot60
Fixed in SVN:                        http://bugs.php.net/fix.php?id=51523&r=fixed
Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=51523&r=needdocs
Fixed in release:                    http://bugs.php.net/fix.php?id=51523&r=alreadyfixed
Need backtrace:                      http://bugs.php.net/fix.php?id=51523&r=needtrace
Need Reproduce Script:               http://bugs.php.net/fix.php?id=51523&r=needscript
Try newer version:                   http://bugs.php.net/fix.php?id=51523&r=oldversion
Not developer issue:                 http://bugs.php.net/fix.php?id=51523&r=support
Expected behavior:                   http://bugs.php.net/fix.php?id=51523&r=notwrong
Not enough info:                     http://bugs.php.net/fix.php?id=51523&r=notenoughinfo
Submitted twice:                     http://bugs.php.net/fix.php?id=51523&r=submittedtwice
register_globals:                    http://bugs.php.net/fix.php?id=51523&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=51523&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=51523&r=dst
IIS Stability:                       http://bugs.php.net/fix.php?id=51523&r=isapi
Install GNU Sed:                     http://bugs.php.net/fix.php?id=51523&r=gnused
Floating point limitations:          http://bugs.php.net/fix.php?id=51523&r=float
No Zend Extensions:                  http://bugs.php.net/fix.php?id=51523&r=nozend
MySQL Configuration Error:           http://bugs.php.net/fix.php?id=51523&r=mysqlcfg