This attribute estimates the maximum number of application threads that concurrently access a region entry at one time. This attribute helps optimize the use of system resources and reduce thread contention.

The following declaration sets the region's ConcurrencyLevel to 16:

<region-attributes concurrency-level="16">
Note: When CachingEnabled is false, do not set the ConcurrencyLevel attribute. An IllegalStateException is thrown if the attribute is set.