Thread Pool Sizing; Examining Iiop Messages; Sun Glassfish Enterprise Server 2.1 Performance Tuning Guide • January - Sun Microsystems Sun GlassFish Enterprise Server 2.1 Tuning Manual

ORB Settings
Load Balancing
For information on how to configure RMI/IIOP for multiple application server instances in a
cluster,
Server 2.1 High Availability Administration
When tuning the client ORB for load-balancing and connections, consider the number of
connections opened on the server ORB. Start from a low number of connections and then
increase it to observe any performance benefits. A connection to the server translates to an ORB
thread reading actively from the connection (these threads are not pooled, but exist currently
for the lifetime of the connection).

Thread Pool Sizing

After examining the number of inbound and outbound connections as explained above, tune
the size of the thread pool appropriately. This can affect performance and response times
significantly.
The size computation takes into account the number of client requests to be processed
concurrently, the resource (number of CPUs and amount of memory) available on the machine
and the response times required for processing the client requests.
Setting the size to a very small value can affect the ability of the server to process requests
concurrently, thus affecting the response times since requests will sit longer in the task queue.
On the other hand, having a large number of worker threads to service requests can also be
detrimental because they consume system resources, which increases concurrency. This can
mean that threads take longer to acquire shared structures in the EJB container, thus affecting
response times.
The worker thread pool is also used for the EJB container's housekeeping activity such as
trimming the pools and caches. This activity needs to be accounted for also when determining
the size. Having too many ORB worker threads is detrimental for performance since the server
has to maintain all these threads. The idle threads are destroyed after the idle thread timeout
period.

Examining IIOP Messages

It is sometimes useful to examine the IIOP messages passed by the Enterprise Server. To make
the server save IIOP messages to the server.log file, set the JVM option
-Dcom.sun.CORBA.ORBDebug=giop. Use the same option on the client ORB.
The following is an example of IIOP messages saved to the server log. Note: in the actual output,
each line is preceded by the timestamp, such as [29/Aug/2002:22:41:43] INFO (27179):
CORE3282: stdout.
74 Sun GlassFish Enterprise Server 2.1 Performance Tuning Guide • January 2009
Chapter 9, "RMI-IIOP Load Balancing and Failover, " in Sun GlassFish Enterprise
Guide.