Infinispan users worried about memory consumption should upgrade to Infinispan 5.3.0.Final as soon as possible, because as part of the work we’ve done to support storing byte arrays without wrappers, and the development of the interoperability mode, we’ve been working to reduce Infinispan’s memory overhead.

To measure overhead, we’ve used Martin Gencur’s excellent memory consumption tests. The results for entries with 512 bytes are:

Infinispan memory overhead, used in library mode: Infinispan 5.2.0.Final: ~151 bytes Infinispan 5.3.0.Final: ~135 bytes Memory consumption reduction: ~12%

Infinispan memory overhead, for the Hot Rod server: Infinispan 5.2.0.Final: ~174 bytes Infinispan 5.3.0.Final: ~151 bytes Memory consumption reduction: ~15%

Infinispan memory overhead, for the REST server: Infinispan 5.2.0.Final: ~208 bytes Infinispan 5.3.0.Final: ~172 bytes Memory consumption reduction: ~21%

Infinispan memory overhead, for the Memcached server:

Infinispan 5.2.0.Final: ~184 bytes

Infinispan 5.3.0.Final: ~180 bytes Memory consumption reduction: ~2%

This is great news for the Infinispan community but our effort doesn’t end here. We’ll be working on further improvements in next releases to bring down cost even further.

Cheers,

Galder

Have you ever wondered how much Java heap memory is actually consumed when data is stored in Infinispan cache? Let’s look at some numbers obtained through real measurement.

The strategy was the following:

1) Start Infinispan server in local mode (only one server instance, eviction disabled) 2) Keep calling full garbage collection (via JMX or directly via System.gc() when Infinispan is deployed as a library) until the difference in consumed memory by the running server gets under 100kB between two consecutive runs of GC 3) Load the cache with 100MB of data via respective client (or directly store in the cache when Infinispan is deployed as a library) 4) Keep calling the GC until the used memory is stabilised 5) Measure the difference between the final values of consumed memory after the first and second cycle of GC runs 6) Repeat steps 3, 4 and 5 four times to get an average value (first iteration ignored)

The amount of consumed memory was obtained from a verbose GC log (related JVM options: -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Xloggc:/tmp/gc.log)

The test output looks like this: https://gist.github.com/4512589

The operating system (Ubuntu) as well as JVM (Oracle JDK 1.6) were 64-bit. Infinispan 5.2.0.Beta6. Keys were kept intentionally small (10 character Strings) with byte arrays as values. The target entry size is a sum of key size and value size.