Here goes with my first posting to this list.
I've been working on performance for an application that uses Tomcat, JBoss, JBossMQ,
a couple of
queues and 1 message driven bean. Response times were fine until I started loading
the server
with multiple concurrent connections. Until I did some work with it, the application
slowed down
dramatically under reasonable loads (10 to 50 concurrent clients). One of the
problems I found
along the way looks to be a problem with the implementation of SpyObjectMessage.
I found that calls to ObjectMessage.getObject() and ObjectMessage.setObjet() were
increasing
significantly in execution time under reasonable loads. With a single client the
times were
around 1/10th of a second but with 10 to 50 concurrent clients they went up to over a
second. I
found that it is faster to convert the data to XML, send it as a TextMessage and parse
it on the
other side.
I can't explain this completely because the code for SpyObjectMessage in the version
of JBossMQ
I'm using (JBoss-2.2.2_Tomcat-3.2.2) is not in the distribution (why is this?).
However, looking
at the current code of SpyObjectMessage I see some code that definitely won't perform
well. The
problem is that setObject() serializes the object and getObject() deserializes it
every time it is
invoked. I realize that you need a serialized version for writeExternal(), but why
must the
memory representation be serialized? In my case it was not a persistant message
anyway so
writeExternal() should never get called. Is there something in the spec that says
that each
client of an object message must get a different instance of the object? That's the
only reason I
can think of for this behavior. If it's not required by the spec (which I don't think
it is),
then the only affect of this serialization/deserialization is to slow things down,
especially for
CPU bound apps.
The fix is trivial. Store the Object as an Object and serialize or deserialize it
only when
necessary in writeExternal() and readExternal().
Am I missing something here or is this a real problem?
Matt Cleveland
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