I'm in the middle of some optimizations so I'm still collecting that data. However, I can say that ~50% of the consumed memory (250MB total used) was coming from ConcurrentHashMaps and the maps were practically "empty". There are/were 2 places using those maps 1) MINA and 2) Openfire internal though most of them were MINA related. Once I run the test again with no Openfire refs to those maps I will provide the info you requested. And if I have some time I will change locally MINA to use HashMaps and compare (though I cannot promise I will have enough time).
Regards, -- Gato -----Original Message----- From: James Im [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 19, 2007 11:44 PM To: dev@mina.apache.org Subject: Re: Possible optimization? I think it might be a good change BUT you didn't say how big was the benefit of this change on memory consumption. Could you tell us how much memory the JVM was using before and after the change under the same load? Gaston Dombiak wrote: >Hey, > > > >We are opening 60K concurrent connections to Openfire and generating >some heap dumps to analyze memory consumption. And we found something >that really surprised us since we never heard about it. A very big part >of the total memory is being consumed by ConcurrentHashMaps. The >ConcurrentHashMap uses internal objects to keep track of its content and >even if you have an "empty" ConcurrentHashMap the map will create as >many segments as its default size. > > > >Tracing the references I see that BaseIoSession uses a ConcurrentHashMap >to keep track of the session attributes. Based on this finding I made >some changes to Openfire so that not highly concurrent code and heavily >used code would use synchronized + HashMap (the old style we can say) >instead of a ConcurrentHashMap. I don't see that MINA uses the session >attributes and in the Openfire's case the usage of those attributes is >high (but not that high) and never concurrent. So what do you think of >changing BaseIoSession to use a HashMap and use synchronized block when >accessing that variable? HashMap also uses internal objects but they are >smaller and less objects. > > > >Regards, > > > > -- Gato > > _________________________________________________________________ Få de bedste søgeresultater med MSN Search: http://search.msn.dk
