Increase RLIMIT MEMLOCK ulimit – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-6.8

Briefly, this error occurs when Elasticsearch is unable to lock the memory because the memory lock limit (RLIMIT_MEMLOCK) is too low. This can lead to swapping, which can degrade Elasticsearch performance. To resolve this issue, you can increase the RLIMIT_MEMLOCK ulimit. This can be done by editing the limits.conf file (usually located in /etc/security/limits.conf) and adding or modifying the lines for the Elasticsearch user to increase the hard and soft limits. Alternatively, you can disable memory swapping altogether, but this may have other performance implications.

This guide will help you check for common problems that cause the log ” Increase RLIMIT_MEMLOCK (ulimit). ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: bootstrap.

Log Context

Log “Increase RLIMIT_MEMLOCK (ulimit).” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                                 user; user; user
                    logger.warn("If you are logged in interactively; you will have to re-login for the new limits to take effect.");
            } else {
                logger.warn("Increase RLIMIT_MEMLOCK (ulimit).");

    static void trySetMaxNumberOfThreads() {


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