Bug #81113 [Com]: PDO holds some non-GCable reference
Edit report at https://bugs.php.net/bug.php?id=81113&edit=1
ID: 81113
Comment by: m at m dot cz
Reported by: m at m dot cz
Summary: PDO holds some non-GCable reference
Status: Open
Type: Bug
Package: PDO related
Operating System: any
PHP Version: 8.0.7
Block user comment: N
Private report: N
New Comment:
I have futher looked into this issue with following:
a) the main issue is that PHPUnit TestCase is instanciated per test (correct), but PHPUnit does not
destroy these instances after the test is completed, but keep that instances referenced until all
tests are done (wrong, but PHP works correctly). PHPUnit issue: https://github.com/sebastianbergmann/phpunit/issues/4705
b) https://github.com/atk4/data/commit/0c152f228d27a4ff81223387d881cd7324fe0fb4#diff-2396b34d8258dc49e2597630cd485205d02402dbbc6dd7704c8493cbf9a6ea04R42
even then gc_collect_cycles() is needed to be called at least twice. Reported as https://bugs.php.net/bug.php?id=81117.
This bug report can be closed.
Previous Comments:
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[2021-06-08 12:44:39] nikic@php.net
I tried this script https://gist.github.com/nikic/a55b70d6b7c1acf6785c7e50c37754dc
based on the dbal issue, but it does not show a memory leak on PHP 8.1 (or PHP 8.0, or PHP 7.4). So
whatever issue that hit, it seems to have been fixed. The memory leak reported in bug #75190 is also
fixed.
If there is some reasonably minimal way to reproduce, I'm happy to address other GC problems as
well. I don't want to reduce this down from "using doctrine dbal, somewhere, somehow"
though.
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[2021-06-08 12:31:53] m at m dot cz
It seems it is related with:
https://github.com/doctrine/dbal/issues/3047
and
https://bugs.php.net/bug.php?id=75190
which describes a GC issue when PDO class is extended, hovewer, it is marked as "not a
bug". Why it is not a bug or is it technically impossible to provide full GC support?
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[2021-06-08 11:52:05] nikic@php.net
Okay, I think this will need some more reduced code to make progress. PDO generally does support GC,
and since PHP 8.1 also supports per-driver GC. So this probably requires that some specific feature
is being used.
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[2021-06-08 09:31:44] m at m dot cz
At least pdo_mysql is affected, as when max. connection count is limited (by ALTER USER user@% WITH
MAX_USER_CONNECTIONS 10;), connection limit is hit.
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[2021-06-08 08:52:19] nikic@php.net
Which PDO driver do you use?
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