PHP-FPM PHP Warning: require(): Unable to allocate memory for pool

Are you using APC Cache ? You can check via SSH command

Code:

php --ri apc

which would output something like

Code:

apc

APC Support => enabled
Version => 3.1.15-dev
APC Debugging => Disabled
MMAP Support => Enabled
MMAP File Mask =>
Locking type => pthread mutex Locks
Serialization Support => php, igbinary
Revision => $Revision: 330418 $
Build Date => Jun 21 2014 13:13:45

Directive => Local Value => Master Value
apc.enabled => On => On
apc.shm_segments => 1 => 1
apc.shm_size => 32M => 32M
apc.shm_strings_buffer => 4M => 4M
apc.include_once_override => Off => Off
apc.num_files_hint => 4096 => 4096
apc.user_entries_hint => 4096 => 4096
apc.gc_ttl => 3600 => 3600
apc.ttl => 7200 => 7200
apc.user_ttl => 7200 => 7200
apc.mmap_file_mask => no value => no value
apc.filters => no value => no value
apc.cache_by_default => On => On
apc.file_update_protection => 2 => 2
apc.enable_cli => On => On
apc.max_file_size => 1M => 1M
apc.stat => On => On
apc.canonicalize => On => On
apc.stat_ctime => Off => Off
apc.write_lock => On => On
apc.slam_defense => Off => Off
apc.report_autofilter => Off => Off
apc.rfc1867 => Off => Off
apc.rfc1867_prefix => upload_ => upload_
apc.rfc1867_name => APC_UPLOAD_PROGRESS => APC_UPLOAD_PROGRESS
apc.rfc1867_freq => 0 => 0
apc.rfc1867_ttl => 3600 => 3600
apc.coredump_unmap => Off => Off
apc.preload_path => no value => no value
apc.file_md5 => Off => Off
apc.use_request_time => On => On
apc.lazy_functions => Off => Off
apc.lazy_classes => Off => Off
apc.serializer => igbinary => igbinary
apc.enable_opcode_cache => On => On

If you are then most likely APC Cache memory allocation is too low as the default is 32M for low memory systems as defined by apc.shm_size = 32M in /etc/centminmod/php.d/apc.ini file.

Then restart php-fpm service via

Code:

service php-fpm restart

or command shortcut

Code:

fpmrestart

You can find all your php ini file locations via command

Code:

php --ini

which would output something like the following

Code:

Configuration File (php.ini) Path: /usr/local/lib
Loaded Configuration File:         /usr/local/lib/php.ini
Scan for additional .ini files in: /etc/centminmod/php.d
Additional .ini files parsed:      /etc/centminmod/php.d/apc.ini,
/etc/centminmod/php.d/igbinary.ini,
/etc/centminmod/php.d/imagick.ini,
/etc/centminmod/php.d/memcache.ini,
/etc/centminmod/php.d/memcached.ini

 

Use your APC stats page to monitor and adjust memory allocation to your specific needs

First, edit user/pass in /usr/local/nginx/html/${N}_myapc.php

where $N is a number, you can find what it is via

Code:

ls -lah /usr/local/nginx/html/*_myapc.php

Second, password protect _myapc.php file. To password protect your ${N}_myapc.php file at /usr/local/nginx/html
you need to do 3 steps:

#############################################################
1). Use htpasswd.py script at /usr/local/nginx/conf/htpasswd.py to setup
username and password using following command:

Code:

  python /usr/local/nginx/conf/htpasswd.py -b /usr/local/nginx/conf/htpasswd yourusername yourpassword

change yourusername and yourpassword to unique values of your own.

#############################################################
2). Add the following 6 lines of code to your main nginx virtual host file
/usr/local/nginx/conf/conf.d/virtual.conf first server{} entry. Changing ${N} in the location to your specific unique number prefix.

6 lines of code:

Code:

location ~ ^/${N}_myapc\.php$ {
auth_basic "Private";
auth_basic_user_file /usr/local/nginx/conf/htpasswd;
include /usr/local/nginx/conf/staticfiles.conf;
include /usr/local/nginx/conf/php.conf;
}

End result for first server{} entry looks like below:

Code:

server {
            listen   80;
            server_name yourhostname.com;
            root   html;

        access_log              /var/log/nginx/localhost.access.log     main buffer=32k;
        error_log               /var/log/nginx/localhost.error.log      error;

# ngx_pagespeed & ngx_pagespeed handler
#include /usr/local/nginx/conf/pagespeed.conf;
#include /usr/local/nginx/conf/pagespeedhandler.conf;
#include /usr/local/nginx/conf/pagespeedstatslog.conf;

# limit_conn limit_per_ip 16;
# ssi  on;

            location / {

#               Enables directory listings when index file not found
#               autoindex  on;

#               Shows file listing times as local time
#               autoindex_localtime on;

#               Enable for vBulletin usage WITHOUT vbSEO installed
#               try_files               $uri $uri/ /index.php;

            }

location ~ ^/${N}_myapc\.php$ {
auth_basic "Private";
auth_basic_user_file /usr/local/nginx/conf/htpasswd;
include /usr/local/nginx/conf/staticfiles.conf;
include /usr/local/nginx/conf/php.conf;
}

include /usr/local/nginx/conf/staticfiles.conf;
include /usr/local/nginx/conf/php.conf;
include /usr/local/nginx/conf/drop.conf;
#include /usr/local/nginx/conf/errorpage.conf;

       }

#############################################################
3). Restart Nginx

Code:

service nginx restart

or with command shortcut

Code:

ngxrestart

Then visit the file via your forum host name for the main vhost server_name listed in /usr/local/nginx/conf/conf.d/virtual.conf - yourhostname.com/${N}_myapc.php

 

You have too much fragmentation and near 100% usage. You'd need to bump it up to 256M so maybe 512MB VPS might not be enough

 

it's not the opcache that is the issue, it all depends on the php apps you use and how much cache they require. More php app = more memory consumption