WARNING: Version 5.1 of Elasticsearch has passed its EOL date.
This documentation is no longer being maintained and may be removed. If you are running this version, we strongly advise you to upgrade. For the latest information, see the current release documentation.
When the JVM does a major garbage collection it touches every page of
the heap. If any of those pages are swapped out to disk they will have
to be swapped back in to memory. That causes lots of disk thrashing that
Elasticsearch would much rather use to service requests. There are
several ways to configure a system to disallow swapping. One way is by
requesting the JVM to lock the heap in memory through
or virtual lock (Windows). This is done via the Elasticsearch setting
bootstrap.memory_lock. However, there are cases
where this setting can be passed to Elasticsearch but Elasticsearch is
not able to lock the heap (e.g., if the
elasticsearch user does not
memlock unlimited). The memory lock check verifies that if the
bootstrap.memory_lock setting is enabled, that the JVM was successfully
able to lock the heap. To pass the memory lock check, you might have to