Bug #74833 [Com]: Random crashes, seemingly related to DateTimeImmutable and mod_php

From: Date: Thu, 29 Jun 2017 22:26:00 +0000
Subject: Bug #74833 [Com]: Random crashes, seemingly related to DateTimeImmutable and mod_php
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=74833&edit=1

 ID:                 74833
 Comment by:         mike dot fellows at shaw dot ca
 Reported by:        mike dot fellows at shaw dot ca
 Summary:            Random crashes, seemingly related to
                     DateTimeImmutable and mod_php
 Status:             Open
 Type:               Bug
 Package:            Apache2 related
 Operating System:   Windows 7 64 bit
 PHP Version:        7.1.6
 Block user comment: N
 Private report:     N

 New Comment:

I just re-reviewed the linked Chronos issue and realized that one user has seen this with Apache and
suphp.  So the problem is not exclusive to mod_php.


Previous Comments:
------------------------------------------------------------------------
[2017-06-29 22:12:15] mike dot fellows at shaw dot ca

Description:
------------
The CakePHP project includes a class called Chronos that extends DateTimeImmutable.  It seems to
cause occasional random crashes when run through Apache and mod_php.  In all cases described below
the same PHP software would run flawlessly most of the time, with occasional random crashes (no
changes to the PHP software between everything being OK and crashing).

The crashes have inconsistent symptoms and I have not been able to capture a backtrace.  They are
possibly caused by instantiation of the Chronos class, although this is hard to prove.  Symptoms
include:

- Complaints about the Chronos class containing abstract methods (when it doesn't).  Once this
symptom appears it would continue in this state on page reload.  Eventually Apache usually crashes
given enough page reloads, sometimes witht the zend_mm_heap corrupted mentioned below, somtimes not.
- Sometimes a "zend_mm_heap corrupted" message is placed in the log file followed by a
crash and Apache being restared.
- Sometimes Apache crashes with no log messages.

In all cases restarted Apache would "fix" the problem page for awhile.

I've run the same software using PHP's built in web server and not observed any crashes.

I connected Visual Studio 2015's debugger to the Apache process handling the request - but the
symptoms stopped once the debugger was connected.

Any suggestions for capturing backtraces would be welcome BTW.  I'm currently running Apache
from Apache Lounge and PHP from php.net.

There is copious amounts of information about this bug found here:

https://github.com/cakephp/chronos/issues/147

It seems to have been reported with PHP version 7.0 and up.  My experience has been on Windows 7,
but others have reported similar symptoms with Linux intalls (again with mod_php).

Test script:
---------------
Code can be inspected here for the Class:

https://github.com/cakephp/chronos/blob/master/src/Chronos.php

and here for its interface:

https://github.com/cakephp/chronos/blob/master/src/ChronosInterface.php



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