Bug #63343 [Ana]: Commit failure for repeated persistent connection
Edit report at https://bugs.php.net/bug.php?id=63343&edit=1
ID: 63343
Updated by: nikic@php.net
Reported by: brn at macrovita dot com dot br
Summary: Commit failure for repeated persistent connection
Status: Analyzed
Type: Bug
Package: PDO related
Operating System: Mixed
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
> (from the same request, but even worse also from other requests)
Is that really the case? IIRC the connection pooling is per process/thread, and there can only be
one request per process/thread at a time.
Previous Comments:
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[2021-06-10 10:42:00] cmb@php.net
Actually, Nikita's analysis[1] is spot on:
| The problem as I see it is that destruction of one of the PDO
| objects will always rollback the transaction on the inner object
| (if a transaction is active). In this case this backfires because
| in the meantime another transaction has been opened through a
| different PDO object (but same inner object).
It seems to me that this very issue is only an edge case of the
more general issue that connections that are in use also can be
reused (from the same request, but even worse also from other
requests). I.e. any global state (change) of the connection
(inner object) can affect other code in unforeseen ways.
[1] <https://github.com/php/php-src/pull/2112#discussion_r77312340>
------------------------------------------------------------------------
[2016-09-01 22:32:38] cmb@php.net
This is a memory management issue, as setting $st = null hints
at. Furthermore, assigning the second $db->query() to something
else than $st (e.g. $st1) also lets the script succeed.
The fix for PHP-7.0+ appears to be trivial (see PR #2112), but I
don't know how to solve the problem for PHP-5.6.
------------------------------------------------------------------------
[2016-08-31 23:30:55] cmb@php.net
Confirmed: <https://3v4l.org/iTsHt>.
------------------------------------------------------------------------
[2014-12-17 19:51:42] brn at macrovita dot com dot br
Note: This bug is NOT specific to SQLite.
The original test case uses SQLite just because it makes it simpler to reproduce the problem.
Originally, we ran into this bug with connections against MySQL.
------------------------------------------------------------------------
[2012-10-24 00:06:25] brn at macrovita dot com dot br
Description:
------------
Repeated transaction on repeated persistent PDO connection fails on commit with
'There is no active transaction'.
Reproduced on:
- Fedora 14 32bit PHP 5.3.6
- Gentoo 64bit PHP 5.3.14
We'll work around the bug in application code, but we thought developers might
like to know about this.
// BTM5282
Test script:
---------------
# Should work, but does not:
cat <<'EOD' | php -d display_errors=1 && echo OK
<?php
$db = new PDO('sqlite::memory:', '', '', array(PDO::ATTR_PERSISTENT
=> true));
$db->beginTransaction();
$st = $db->query('select 1');
echo $st->fetchColumn()."\n";
$db->commit();
//$st = null;
$db = new PDO('sqlite::memory:', '', '', array(PDO::ATTR_PERSISTENT
=> true));
$db->beginTransaction();
$st = $db->query('select 2');
echo $st->fetchColumn()."\n";
$db->commit();
EOD
# INTERESTING? -> Works OK with uncommented $st = null;
# Works OK with PDO::ATTR_PERSISTENT => false .
Expected result:
----------------
1
2
OK
Actual result:
--------------
Fatal error: Uncaught exception 'PDOException'
with message 'There is no active transaction' in -:11 ...
------------------------------------------------------------------------
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