Class loading issue by using Jaxb

After Monitoring our JVM by Jconsole/JvisalVM, I found the Perm Gen is not that stable and will perform Full GC after a short interval, meanwhile, the trend of total class loaded number is going up almost linear...

However Jconsole/JvisalVM only give me a rough idea that we got a problem on class loading or we just guess we may "dynamically creating new classes on the fly".




The simplest way to retrieve class loading information is to check the Verbose output check-box on Jconsole, so that you can trace the class loading event on command window where you started your service.


Here is some of loaded class information which caused the trouble we identify, Each new JAXB context would dynamically generate new classes instead of reusing the existing one:

[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_responseOID from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_respondDate from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_respondDate from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusRespondDate from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusRespondDate from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusOID from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusOID from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusCode from __JVM_DefineClass__]
[Loaded com.whatever.v2_0.RespondedDateRangeSummary$JaxbAccessor
F_statusCode from __JVM_DefineClass__]

Here is one potential solution on this similar problem, you can try that:
http://fleets.wordpress.com/2010/01/08/jaxb-memory-leak-with-metro-too-many-loaded-classes/

And also in HornetQ performance tuning " Avoiding Anti-Patterns", the first item is that "Re-use connections / sessions / consumers / producers", so we should Always re-use them instead of create new one. And also you could add -XX:+TraceClassLoading and -XX:+TraceClassUnloading for your running production to trace those information instead.