Edit report at https://bugs.php.net/bug.php?id=65387&edit=1
ID: 65387
Comment by: php dot net at ss dot st dot tc
Reported by: bugs dot php dot net at ss dot chernousov dot net
Summary: Circular references in SPL iterators are not garbage
collected
Status: Closed
Type: Bug
Package: Scripting Engine problem
Operating System: Any
PHP Version: 5.5.1
Assigned To: nikic
Block user comment: N
Private report: N
New Comment:
The bug author here.
Thank you for fixing the issue with SPL iterators. However, the original issue was about circular
references on callbacks in general, and not specifically about handling circular references in SPL
iterators. I see the bug title was changed on 2020-10-01, affecting its meaning quite much. Among
the 6 cases provided (https://gist.github.com/5lava/53aa2e53c7f8c658f045), only one of them had to
do with SPL iterators. I tested that case and I confirm it's fixed, but the 2nd one still
leaks, as it did 7 years ago.
I did not re-test cases 3-6 since then, they are rather specific and I don't know if
that's something that has to be addressed in the corresponding extensions or PHP core itself.
That does not, however, diminish the scale of the problem. For example, with curl:
// TEST 7: curl callback
$obj->a = curl_init('https://www.php.net/');
curl_setopt($obj->a, CURLOPT_HEADERFUNCTION, static function() use ($obj) {});
That leaks. Or with PDO/sqlite:
// TEST 8: PDO/sqlite callback
$db = new PDO('sqlite::memory:');
$db->sqliteCreateFunction('md5rev', static function() use ($obj) {}, 1);
That leaks, too. My point being: the bug (the reported one!) was NOT fixed.
@nikic I'd appreciate some input from you regarding this matter. Thank you.
Previous Comments:
------------------------------------------------------------------------
[2020-10-01 14:13:22] nikic@php.net
Automatic comment on behalf of nikita.ppv@gmail.com
Revision: http://git.php.net/?p=php-src.git;a=commit;h=afab9eb48c883766b7870f76f2e2b0a4bd575786
Log: Fix bug #65387
------------------------------------------------------------------------
[2020-09-24 09:09:09] mvorisek at mvorisek dot cz
@nikic why dual_it can not be GCed like any other object and is this something than can be fixed?
https://3v4l.org/AL2Hr the issue seems to be present even if
the callback is static but the (outer) Iterator is linked with any object
------------------------------------------------------------------------
[2020-09-23 20:08:19] nikic@php.net
Related To: Bug #80125
------------------------------------------------------------------------
[2016-03-26 23:40:58] nikic@php.net
Still leaks, even in PHP 7. dual_it doesn't implement GC handling.
------------------------------------------------------------------------
[2013-08-04 20:14:37] bugs dot php dot net at ss dot chernousov dot net
Description:
------------
GC fails to resolve the circular reference if object A retains a reference to a
callback in object B and object B retains a reference to object A. Both objects
leak.
Native PHP stuff like SPL iterators with callbacks and Stream callbacks are also
vulnerable to this problem.
This does not apply to userland PHP objects (i.e. objects of classes that were
defined in PHP scripts by a user).
I provided a test script with a number of tests, including SPL iterators with
callbacks, Stream callbacks, as well as 3rd-party extensions like pecl-event,
pecl-ev, pecl-libevent, pecl-eio.
Test script:
---------------
https://gist.github.com/5lava/53aa2e53c7f8c658f045
Expected result:
----------------
==== NULL ====
==== GC ====
Obj::__destruct
==== THE END ====
or
==== NULL ====
Obj::__destruct
==== GC ====
==== THE END ====
Actual result:
--------------
==== NULL ====
==== GC ====
==== THE END ====
Obj::__destruct
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=65387&edit=1