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Re: [xmlblaster-devel] OutOfMemory Exceptions

Hi Joshua,
mmhh, it sounds strange that the garbage collector does not clean up without human intervention. I really don't know what to say but to give a try to activate the incremental garbage collector (-Xincgc).

java -Xincgc org.xmlBlaster.Main

Btw what jvm and OS are you using ?


Joshua Bowman wrote:

Thank you very much for your help.  I was able to see that the clients
are properly disposing of topics and that nothing is really collecting
on the bus itself.  It appears also that after running the bus for a
couple days, using the garbage collection button in the jconsole returns
memory usage to initial levels.

Is there a way to tell the bus to do its own garbage collection
periodically so that I don't have to enable the jmxremote libraries all
the time?  They appear to slow the system down considerably and I would
like the bus to run without human interaction anyway.

Thanks again!

- Josh

On Tue, 2005-08-30 at 13:11, Marcel Ruff wrote:

Hi Joshua,

please check my last response i send on 2005 08 26,
it should help you further.

If the above doesn't help: You can send a dump of xmlBlaster (from command line just type 'd mydump.xml')
zip it and send it to michele and myself directly after xmlBlaster was
running for a day.


Joshua Bowman wrote:


First, my setup:

I have been tinkering with version 1.0.2 of the bus along with the Perl
client API.  I've got several clients connecting, some of them
exclusively publish-ing, others exclusively get-ing.  The get clients
stay connected and issue a get command every few seconds.  The
publishing clients only connect intermittently--a typical push setup.

Each message has an entirely unique oid, and when a client sees an oid
more than once, it issues an erase command.  Multiple clients may be
get-ing that message, because I'm using XPATH queries that only care
about higher-level taxa, i.e., the unique timestamp at the end of the
oid is ignored when making most queries.

Also, I should point out that I am running the middleware without any
persistence.  (I uncommented all the RAM plugin lines in the
xmlBlaster.properties file)  I've also set the message/maxRemainingLife
to 1000 ms and the destroyDelay to 1 sec.  Typical throughput is
somewhere in the range of a hundred messages/minute.

The server is running Fedora Core 3 on a 2 GHz processor with 1 GB of

Now, the problem:

The middleware and all clients function perfectly for a couple days and
then I start getting exceptions tossed all over.  Especially by the
get-ing clients.  A few examples:

Fault returned from XML RPC Server, fault code 0: java.lang.Exception:
errorCode=legacy message=#exported DOM tree is invalid

Fault returned from XML RPC Server, fault code 0: java.lang.Exception:
errorCode=user.query.invalid message=#exported Sorry, can't access,
query syntax of '/xmlBlaster/key[contains ( at oid,'<unique id>')]' is
wrong : java.lang.NullPointerException

The middleware gives these exceptions:

[Aug 25, 2005 5:09:35 AM WARN  Thread-10 XmlKeyDom.InvalidQuery] Sorry,
can't access, query syntax is wrong for '/xmlBlaster/key[contains
( at oid,'<same unique id as above>')]' : java.lang.NullPointerException


It appears that the clients are properly deleting messages from the bus,
because when I restart a get-ing client, it doesn't recieve any of the
messages that were sent while it was down.  Are these errors due to some
sort of race condition, or am I really running out of memory?

I'm inclined to believe it is the former, because I'm quite new to
xmlBlaster, and I'm fairly certain that I'm abusing the API pretty

Also, I tried getting server stats using the admin commands, but I can't
figure out how to do anything other than these four, which are provided
in the code example:


I'd really like to be able to see some queue details to see how long
messages are hanging around after I think they're supposed to be

Any help will be much appreciated.

- Josh