Squid Proxy WARNING! Your cache is running out of filedescriptors error and solution

by Vivek Gite on June 16, 2008 · 6 comments· last updated at June 18, 2009

I

've Squid Proxy server with over 100 Windows workstation. I see following error message in my cache.log file:

WARNING! Your cache is running out of filedescriptors

Do I need to filter proxy server requests to avoid this problem? How do I fix this problem under CentOS / Fedora / RHEL / Debian Linux?

If you see this message in your /var/log/squid/cache.log file, it means Squid proxy server is running out of file descriptors and cannot handle the extra requests sent by your client computers.

Task: Find out current file descriptors limits

Login to your Squid proxy server and type the following command at shell prompt:

# squidclient mgr:info | grep 'file descri'

# squidclient -p {port} -u {proxy-user} -w '{proxy-password}' mgr:info | grep 'file descri'

# squidclient -p 8080 -u admin -w 'secretePassword' mgr:info | grep 'file descri'

Sample output:

Maximum number of file descriptors: 1024

Available number of file descriptors: 1008

Reserved number of file descriptors: 100

Squid increase the maximum file descriptors

First, update /etc/security/limits.conf file:

# vi /etc/security/limits.conf

Append following line to increase current limit from 1024 to 4096:

* - nofile 4096

Save and close the file. You must re-login to check new limits:

# ulimit -a | grep 'open files'

Sample output:

open files (-n) 4096

Next you need to set the maximum number of open file descriptors by modifying squid proxy server configuration as per your Linux distribution.

Set max_filedesc under RHEL / Red Hat / CentOS / Fedora Linux

Stop the Squid as changes of this value isn't respected by reconfigure command. This value should be changed only if there isn't any active squid process.

# service squid stop

Open /etc/squid/squid.conf file

# vi /etc/squid/squid.conf

Append / add / modify max_filedesc directive:

max_filedesc 4096

Save and close the file. Start the squid proxy server:

# service squid start

Now again run squidclient command or check log files for messages:

# squidclient mgr:info

Set max_filedesc under Ubuntu / Debian Linux

First, stop squid proxy server, enter:

# /etc/init.d/squid stop

OR

$ sudo /etc/init.d/squid stop

Open /etc/default/squid to set max. number of filedescriptors to use. You can increase this on a busy

cache to a maximum of (currently) 4096 filedescriptors. Default is 1024.

$ sudo vi /etc/default/squid

OR

# vi /etc/default/squid

Now set SQUID_MAXFD:

SQUID_MAXFD=4096

Save and close the file. Start the squid proxy server:

$ sudo /etc/init.d/squid start

Verify that it is working with new limits:

# squidclient mgr:info | grep 'file descri'