Container Considerations¶

Java web containers such as Tomcat or Jetty ship with configurations that allow for fast startup, but don’t always deliver the best performance.

Optimize your JVM¶

Set the following performance settings in the Java virtual machine (JVM) for your container. These settings are not specific to any container.

Option	Description
`-server`	Enables the server Java Virtual Machine (JVM), which compiles bytecode much earlier and with stronger optimizations. Startup and initial calls will be slower due to “just-in-time” (JIT) compilation taking longer, but subsequent calls will be faster.
`-Xmx256M -Xms48m`	Allocates extra memory to your server. By default, JVM will use only 64MB of heap. If you’re serving just vector data, you’ll be streaming, so having more memory won’t increase performance. If you’re serving coverages, however, JAI will use a disk cache. `-Xmx256M` allocates 256MB of memory to GeoServer (use more if you have excess memory). It is also a good idea to configure the JAI tile cache size (see the Server Config page in the Web Administration Interface section) so that it uses 75% of the heap (0.75). `-Xms48m` will tell the virtual machine to grab a 48MB heap on startup, which will make heap management more stable during heavy load serving.
`-XX:SoftRefLRUPolicyMSPerMB=36000`	Increases the lifetime of “soft references” in GeoServer. GeoServer uses soft references to cache datastore references and other similar requests. Making them live longer will increase the effectiveness of the cache.
`-XX:MaxPermSize=128m`	Increases the maximum size of permanent generation (or “permgen”) allocated to GeoServer to 128MB. Permgen is the heap portion where the class bytecode is stored. GeoServer uses lots of classes, and it may exhaust that space quickly, leading to out of memory errors. This is especially important if you’re deploying GeoServer along with other applications in the same container, or if you need to deploy multiple GeoServer instances inside the same container.
`-XX:+UseParallelGC`	Enables the throughput garbage collector.

For more information about JVM configuration, see the article Performance tuning garbage collection in Java.