WebSphere/ Performance tuning for JMS

Java heaps

An instance of WebSphere Application Server, with WebSphere Platform Messaging enabled, runs on top of three different processes called regions: the control region (CR), the servant region (SR) and the control region adjunct (CRA). Each region has its own JVM and therefore its independent configuration/tuning:

* The CR is the heart of WebSphere Application Server and handles all intra-region communications. The CR controls the distribution of incoming messages to the several existent SRs. The CR requires a small amount of code and little heap space to operate. Use a heap size of 256MB or more for the CR.
* The SR hosts the EJB container process runs in multiple JVMs for scalability. In the messaging world, the SR runs the MDBs. Because the SR is memory-hungry, use a heap size of 512MB or more.
* There is only one CRA in which the WebSphere Platform Messaging process operates. The CRA is effectively in charge of all the messaging code and requires a substantial heap size. Use a heap size of 512MB or more.


On z/OS system, the messaging engine is executed in its own Java Virtual Machine, often referred to as the CRA. Two important components of the messaging engine run in the CRA: the resource adapter and the Message Store. The resource adapter deals with MDBs. The Message Store is responsible for writing persistent messages to the database.


Tuning MDBs is not trivial. An MDB is a stateless session bean which is missing its home or remote interface. An application cannot invoke an MDB directly but only indirectly by sending a message on a queue on which the MDB is listening. The MDB lives in the EJB container and as such it has to interface with the messaging world through some kind of adapter. On z/OS the container runs in a different process (SR) than the messaging engine (CRA). The code that interfaces the two processes is called the resource adapter and lives part in the SR and part in the CRA.

This adapter defines an object called activation specification that acts as connection factory for the MDBs.



ref:
Performance tuning for Java Messaging Service on WebSphere Application Server on z/OS
http://www.ibm.com/developerworks/websphere/library/techarticles/0608_oriato/0608_oriato.html

tag : WebSphere CR SR CRA

2009-09-06 01:33 : apsrv : コメント : 0 : トラックバック : 0 :
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