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Briefly, this error occurs when OpenSearch is unable to lock the memory it needs due to system limits. The RLIMIT_MEMLOCK is a system setting that controls the maximum memory that can be locked by a process. To resolve this, you can increase the RLIMIT_MEMLOCK limits. This can be done by editing the ‘/etc/security/limits.conf’ file and adding or modifying lines for the OpenSearch user like ‘opensearch soft memlock unlimited’ and ‘opensearch hard memlock unlimited’. Alternatively, you can also set the ‘bootstrap.memory_lock’ setting to ‘false’ in the OpenSearch configuration file, but this may impact performance.
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This guide will help you check for common problems that cause the log ” Increase RLIMIT_MEMLOCK; soft limit: {}; hard limit: {} ” 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; soft limit: {}; hard limit: {}” classname is JNANatives.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :
// mlockall failed for some reason
logger.warn("Unable to lock JVM Memory: error={}; reason={}"; errno ; 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: {}; hard limit: {}"; rlimitToString(softLimit);
rlimitToString(hardLimit));
if (Constants.LINUX) {
// give specific instructions for the linux case to make it easy
String user = System.getProperty("user.name");
logger.warn("These can be adjusted by modifying /etc/security/limits.conf; for example: \n" +
