Increase RLIMIT MEMLOCK ulimit – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch is unable to lock the memory, due to the RLIMIT_MEMLOCK setting being too low. This setting controls the maximum size that may be locked into memory. To resolve this issue, you can increase the RLIMIT_MEMLOCK limit. This can be done by editing the limits.conf file (usually located in /etc/security/limits.conf) and adding or modifying lines for the OpenSearch user to increase the soft and hard limits. Alternatively, you can also set the memlock limit to unlimited. Always ensure to restart the OpenSearch service after making these changes.

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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 OpenSearch concepts: bootstrap.

Log Context

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

                    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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