eAccelerator: shmmax should be at least 2MB

[mrmister]

One of the heaviest pages on one of my sites started returning a blank page and when I ran "tail -f /usr/local/apache/logs/error_log" I had a lot of messages

[Wed Dec 29 13:11:34 2010] [error] [client 94.132.92.237] eAccelerator: shmmax should be at least 2MB
[Wed Dec 29 13:11:34 2010] [error] [client 94.132.92.237] Premature end of script headers: announce.php
[Wed Dec 29 13:11:34 2010] [error] [client 94.132.92.237] File does not exist: /home/user/public_html/500.shtml

What's strange is that everything seems to be OK

# sysctl -a | grep shmmax
kernel.shmmax = 33554432

# cat /proc/sys/kernel/shmmax
33554432

As soon as I did

# /scripts/phpextensionmgr uninstall EAccelerator
Uninstalling EAccelerator
Removing EAccelerator from /usr/local/lib/php.ini

The page started working fine. Any ideas on what might be the issue?

WHM 11.28.60
CENTOS 5.5 i686 virtuozzo

WITHOUT EAccelerator with page working:

top - 14:06:13 up 2 days, 23:45, 1 user, load average: 0.00, 0.00, 0.00
Tasks: 52 total, 1 running, 50 sleeping, 0 stopped, 1 zombie
Cpu(s): 0.0%us, 0.2%sy, 0.5%ni, 98.9%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 524288k total, 194884k used, 329404k free, 0k buffers
Swap: 0k total, 0k used, 0k free, 0k cached

WITH EAccelerator with page not working:

top - 14:10:03 up 2 days, 23:48, 1 user, load average: 0.15, 0.06, 0.02
Tasks: 57 total, 1 running, 54 sleeping, 0 stopped, 2 zombie
Cpu(s): 0.0%us, 0.2%sy, 0.5%ni, 98.9%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 524288k total, 211448k used, 312840k free, 0k buffers
Swap: 0k total, 0k used, 0k free, 0k cached

# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/simfs 20G 6.6G 14G 34% /
none 256M 4.0K 256M 1% /dev

FROM PHPINFO():

System Linux server.domain.tld 2.6.18-194.26.1.el5.028stab079.1 #1 SMP Sat Nov 27 00:56:10 MSK 2010 i686

This program makes use of the Zend Scripting Language Engine:
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
with eAccelerator v0.9.6.1, Copyright (c) 2004-2010 eAccelerator, by eAccelerator
with the ionCube PHP Loader v3.3.20, Copyright (c) 2002-2010, by ionCube Ltd.

eAccelerator
eAccelerator support enabled
Version 0.9.6.1
Caching Enabled true
Optimizer Enabled true
Check mtime Enabled true
Memory Size 16,777,176 Bytes
Memory Available 16,263,372 Bytes
Memory Allocated 513,804 Bytes
Cached Scripts 10
Removed Scripts 0

Directive Local Value Master Value
eaccelerator.allowed_admin_path no value no value
eaccelerator.cache_dir /tmp/eaccelerator /tmp/eaccelerator
eaccelerator.check_mtime 1 1
eaccelerator.debug 0 0
eaccelerator.enable 1 1
eaccelerator.filter no value no value
eaccelerator.log_file no value no value
eaccelerator.optimizer 1 1
eaccelerator.shm_max 0 0
eaccelerator.shm_only 0 0
eaccelerator.shm_prune_period 0 0
eaccelerator.shm_size 16 16
eaccelerator.shm_ttl 0 0

[cPanelDon]

As the system is a Virtuozzo/OpenVZ-based virtual environment I would make sure the VPS container has sufficient resources allocated; you may use the following command to help check certain limitations imposed by the hardware node configuration of the virtual environment:

# cat /proc/user_beancounters

If providing the above output, I recommend to place it within the BBcode "CODE" tags for easier readability.

The FAQ on the official eAccelerator web site includes VPS-specific information: FAQ – eAccelerator

If you are using VPS solution, make sure the share memory and socket buffers in VPS configuration are sufficient. For OpenVZ or similar type, you can check them by cat /proc/user_beancounter. In normal case all the fail count (failcnt) should be zero. You would need to ask your VPS provider to enlarge the barrier and limit value if you encountered any fail count increase once failed loading eaccelerator.

In case you have direct control over the VPS container configuration from the hardware node, I recommend referring to the following documentation about setting or changing the VPS resource limitations and related parameters:

• Setting UBC parameters - OpenVZ Wiki
• User Guide/Managing Resources - OpenVZ Wiki
• UBC primary parameters - OpenVZ Wiki
• UBC secondary parameters - OpenVZ Wiki
• UBC auxiliary parameters - OpenVZ Wiki
• UBC parameters table - OpenVZ Wiki

Related documentation: shmpages - UBC auxiliary parameters - OpenVZ Wiki

shmpages
The total size of shared memory (IPC, shared anonymous mappings and tmpfs objects).

These pages are also accounted into privvmpages.

The barrier should be set equal to the limit. The configuration of this parameter doesn't affect security and stability of the whole system or isolation between containers. Its configuration affects functionality and resource shortage reaction of applications in the given container only.