Doc #75247 [Opn->Csd]: Documentation Recommends Broken Setting
| From: | nikic@php.net | Date: | Mon, 18 Dec 2017 20:54:42 +0000 |
| Subject: | Doc #75247 [Opn->Csd]: Documentation Recommends Broken Setting | ||
| References: | 1 | Groups: | php.doc.bugs |
| Request: | Send a blank email to doc-bugs+get-15294@lists.php.net to get a copy of this message | ||
Edit report at https://bugs.php.net/bug.php?id=75247&edit=1
ID: 75247
Updated by: nikic@php.net
Reported by: pegasus at vaultwiki dot org
Summary: Documentation Recommends Broken Setting
-Status: Open
+Status: Closed
Type: Documentation Problem
Package: opcache
PHP Version: 5.6.31
-Assigned To:
+Assigned To: nikic
Block user comment: N
Private report: N
New Comment:
As far as I'm aware there haven't been issues with opcache.fast_shutdown in PHP 7. As of
PHP 7.2 the ini option is removed, as fast_shutdown is now integrated in core PHP. I've just
pushed a doc change to that effect.
Previous Comments:
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[2017-09-22 19:47:34] pegasus at vaultwiki dot org
See also this PHP bug report, providing case-in-point, which has gone ignored for over 2 years even
though the requested information was provided: https://bugs.php.net/bug.php?id=69190
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[2017-09-22 19:25:22] pegasus at vaultwiki dot org
Description:
------------
---
From manual page: http://www.php.net/opcache.installation
---
The page recommends using directive opcache.fast_shutdown = 1, however this directive is known to be
broken. See the following Zend bug which has remained unsolved since 2013: https://github.com/zendtech/ZendOptimizerPlus/issues/146
In my experiences on many clients' servers, fast_shutdown occasionally caused PHP<->web
server communication to fail and the PHP process to crash in random places without a segfault. In a
number of cases, this led to database corruption. Disabling opcache.fast_shutdown always resolved
the issue.
Since opcache.fast_shutdown bypasses PHP garbage collection in favor of Zend MM garbage collection,
it is likely that Zend MM is not doing this successfully, possibly creating a
Use-Again-Without-Free? situation which causes the next process to crash. However, without segfaults
to provide information, this is only a theory.
Expected result:
----------------
The documentation should not recommend opcache.fast_shutdown = 1 until the Zend bug is fixed: https://github.com/zendtech/ZendOptimizerPlus/issues/146
If the Zend bug is fixed, the documentation should specify which version(s) of PHP the fix applies
in, and therefore which version of PHP opcache.fast_shutdown becomes safe to use again.
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Edit this bug report at https://bugs.php.net/bug.php?id=75247&edit=1