Increase RLIMIT MEMLOCK soft limit – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch tries to lock the memory but fails due to insufficient memory lock limit. Elasticsearch uses memory locking to prevent swapping of its memory, which can degrade performance. To resolve this issue, you can increase the RLIMIT_MEMLOCK soft limit in the operating system settings. Alternatively, you can disable memory locking in the Elasticsearch configuration by setting bootstrap.memory_lock to false. However, this may lead to swapping and reduced performance. Another solution is to add the Elasticsearch user to the ‘memlock unlimited’ line in the limits.conf file.

This guide will help you check for common problems that cause the log ” Increase RLIMIT_MEMLOCK; soft limit: ” 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; soft limit:” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

         // mlockall failed for some reason
        logger.warn("Unable to lock JVM Memory: error=" + errno + ";reason=" + errMsg);
        logger.warn("This can result in part of the JVM being swapped out.");
        if (errno == JNACLibrary.ENOMEM) {
            if (rlimitSuccess) {
                logger.warn("Increase RLIMIT_MEMLOCK; soft limit: " + rlimitToString(softLimit) + "; hard limit: " + rlimitToString(hardLimit));
                if (Constants.LINUX) {
                    // give specific instructions for the linux case to make it easy
                    String user = System.getProperty("");
                    logger.warn("These can be adjusted by modifying /etc/security/limits.conf; for example: \n" +
                                "\t# allow user '" + user + "' mlockall\n" +


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