memcached: Failed To Set rlimit For Open Files Error and Solution

The "Failed to set rlimit for open files" error is a common issue that can occur when starting the memcached daemon on a Linux or Unix system. This error can be caused by a variety of factors, including a lack of permissions, a low open file limit, or a problem with the memcached configuration.

To resolve the "Failed to set rlimit for open files" error when starting memcached, you can try the following steps:

1. Check the permissions of the memcached daemon:

The memcached daemon may require certain permissions to set the open file limit. You can check the permissions of the memcached daemon by running the following command:

ls -l /path/to/memcached

Replace /path/to/memcached with the path to the memcached executable.

If the memcached daemon does not have the necessary permissions, you can try changing the permissions of the memcached executable to allow it to set the open file limit.

2. Check the open file limit:

The open file limit is a system setting that determines the maximum number of open files that a process can have at any given time. If the open file limit is too low, the memcached daemon may be unable to set the open file limit to a higher value.

To check the open file limit, you can use the ulimit command:

ulimit -n

This will print the current open file limit to the console.

If the open file limit is too low, you can increase it by adding the following line to the /etc/security/limits.conf file:

* soft nofile 65535
* hard nofile 65535

This will increase the open file limit to 65535 for all users.

Keep in mind that the open file limit may also be set in other configuration files, such as /etc/pam.d/common-session. You should check all relevant configuration files to ensure that the open file limit is set to an appropriate value.

3. Check the memcached configuration:

The "Failed to set rlimit for open files" error may also be caused by a problem with the memcached configuration. You can check the memcached configuration file, typically located at /etc/memcached.conf, for any issues.

For example, if the -u option is set to a user that does not have the necessary permissions to set the open file limit, the "Failed to set rlimit for open files" error may occur.

You can try modifying the memcached configuration to resolve the issue.