A critical performance tuning parameter for Oracle Service Bus (OSB) is the setting for RouterRuntimeCache. The following article describes this parameter and the impact of changes to it.
Many customers start out with smaller projects for an initial release. Typically, these applications require 20-30 Proxy services. But as time goes on and later phases of the project rollout, the number of proxy services can increase drastically. The RouterRuntimeCache is a cache implemented by OSB to improve performance by eliminating or reducing the amount of time spent on compiling the proxy pipeline.
By default, OSB will not compile a pipeline until a request message for a given service is received. Once it has been compiled, the pipeline is cached in memory for re-use. You have probably noticed in testing that the first request to a service takes longer to respond than subsequent requests, and this is a big part of the reason. Since free heap space is often at a premium, this cache can not be infinite in size so this cache has a built in limit. When the cache is full, the least recently used entry is released and the pipeline that is currently being requested is placed into cache in its place. The next time a request comes in for the service who's pipeline was released, that pipeline has to be re-compiled and placed in cache, again forcing out the least recently used pipeline. Once a pipeline is placed in cache it is never removed from cache unless forced out by a full cache scenario as above, or if the service is updated, forcing it to be recompiled.
The default size limit of the RouterRuntimeCache is 100 entries (or pipelines). It is limited by the number of services in the cache, not the memory used by the cache so the amount of memory used by a full cache will vary greatly based on the complexity of the services, the extent and complexity of inline xquery, etc. If your project grows beyond 100 proxy services, system performance can degrade significantly if the cache size is not increased to hold all frequently used services.
Unfortunately, the way to tune this cache is not exposed through the OSB console. As of 11g PS5, the only way to set this parameter is via a system property specified on the Java command-line. The property name is com.bea.wli.sb.pipeline.RouterRuntimeCache.size. For example,
“java … -Dcom.bea.wli.sb.pipeline.RouterRuntimeCache.size=500 …
In this example, OSB will cache 500 proxies, instead of the default 100. Because increasing the RouterRuntimeCache.size value will require more space in the heap to hold the additional proxies, be aware that you may need to reevaluate your JVM memory settings to allow OSB to continue to perform optimally.