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
-Xms128m By starting with a larger heap GeoServer will not need to pause and ask the operating system for more memory during heavy load. The setting -Xms128m will tell the virtual machine to acquire grab a 128m heap memory on initial startup.
-Xmx756M Defines an upper limit on how much heap memory Java will request from the operating system (use more if you have excess memory). By default, the JVM will use 1/4 of available system memory. The setting -Xms756m allocates 756MB of memory to GeoServer.
-XX:MaxPermSize=512m This setting is no longer needed for Java 8 to to a change in how applications are loaded. Previously we asked administrators to rase this value as GeoServer is a relatively large application.
-XX:SoftRefLRUPolicyMSPerMB=36000 Increases the lifetime of “soft references” in GeoServer. GeoServer uses soft references to cache datastore, spatial reference systems, and other data structures. By increasing this value to 36000 (which is 36 seconds) these values will stay in memory longer increasing the effectiveness of the cache.
-XX:+UseParallelGC The default garbage collector, pauses the application while using several threads to recover memory. Recommended if your GeoServer will be under light load and can tolerate pauses to clean up memory.
--XX:+UseParNewGC Enables use of the concurrent mark sweep (CMS) garbage collector uses multiple threads to recover memory while the application is running. Recommended for GeoServer under continuous use, with heap sizes of less than 6GB.
–XX:+UseG1GC Enables use of the Garbage First Garbage Collector (G1) using background threads to scan memory while the application is running prior to cleanup. Recommended for GeoServer under continuous load and heap sizes of 6GB or more. Additionally you may experiment with -XX:+UseStringDeduplicationJVM to ask G1 to better manage common text strings in memory.

For more information about JVM configuration, see the article Performance tuning garbage collection in Java and The 4 Java Garbage Collectors.


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, image processing will use a tile cache and benifit from more memory. As an administrator you can configure the portion of memory available as a tile cache (see the Server Config page in the Web administration interface section) - for example to use 0.75 to allocate 75% of the heap as a tile cache.


You can try out memory settings on the command line to check settings/defaults prior to use.

To check settings use java -Xms128m -Xmx756m -XX:+PrintFlagsFinal -version | grep HeapSize:

uintx InitialHeapSize   := 134217728     {product}
uintx MaxHeapSize       := 792723456     {product}

Which when converted from bytes matches 128 MB initial heap size, and 512 MB max heap size.

Check defaults for your hardware using java -XX:+PrintFlagsFinal -version | grep HeapSize:

uintx InitialHeapSize   := 268435456     {product}
uintx MaxHeapSize       := 4294967296    {product}

The above results (from a 16 GB laptop) amount to initial heap size of 256m, and a max heap size of around 4 GB (or around 1/4 of system memory).