Re: Memory leak after calling exit() when Zend MM is turned off?
On 16 בינו 2013, at 22:00, Pascal Mathis <[email protected]> wrote:
> Hi internals!
>
> I am currently developing a Zend extension. Because the Zend MM leak reports are not really
> useful sometimes, I switched the memory manager off with the environment variable USE_ZEND_ALLOC=0,
> so that I can use valgrind.
>
> Right now I have found some kind of memory leak. You can use every script which has an
> exit()-call to reproduce this leak. For example:
>
> <?php exit("Memory leak example.\n"); ?>
>
> If you run this PHP script with valgrind, it will report some ugly memory leak:
>
> valgrind version: valgrind-3.6.0.SVN-Debian
> PHP Version: 5.4.10 (debug)
> Configure options: --disable-all --disable-cgi --enable-debug
> ---
> Command: export USE_ZEND_ALLOC=0 && valgrind --leak-check=full php-5.4.10-debug
> test.php
> ---
> Report:
> ==5693== HEAP SUMMARY:
> ==5693== in use at exit: 420 bytes in 4 blocks
> ==5693== total heap usage: 8,355 allocs, 8,351 frees, 2,503,705 bytes allocated
> ==5693==
> ==5693== 420 (240 direct, 180 indirect) bytes in 1 blocks are definitely lost in loss record 4
> of
> ==5693== at 0x4C244E8: malloc (vg_replace_malloc.c:236)
> ==5693== by 0x5E08C4: _emalloc (zend_alloc.c:2423)
> ==5693== by 0x5C11C3: compile_file (zend_language_scanner.l:551)
> ==5693== by 0x617311: zend_execute_scripts (zend.c:1301)
> ==5693== by 0x58A22F: php_execute_script (main.c:2482)
> ==5693== by 0x768967: do_cli (php_cli.c:988)
> ==5693== by 0x76987C: main (php_cli.c:1364)
> ==5693==
> ==5693== LEAK SUMMARY:
> ==5693== definitely lost: 240 bytes in 1 blocks
> ==5693== indirectly lost: 180 bytes in 3 blocks
> ==5693== possibly lost: 0 bytes in 0 blocks
> ==5693== still reachable: 0 bytes in 0 blocks
> ==5693== suppressed: 0 bytes in 0 blocks
>
> When the Zend memory manager is turned on, everything is fine. Is this behavior intended?
Yes. The implementation of exit() will not necessarily free all
allocated blocks. It therefore intentionally suppresses errors that
might come from the memory manager regarding leaks - but if you turn
off the memory manager and use valgrind - you'd see them. It's not a
problem unless you actually use PHP without the memory manager in
production, which of course you should not.
Zeev
Thread (3 messages)