Woops, should have gone to dev@ list ---------- Forwarded message ---------- From: Niall Pemberton <[EMAIL PROTECTED]> Date: Aug 7, 2007 2:36 AM Subject: Re: Circular Reference on WeakHashMap To: Clebert Suconic <[EMAIL PROTECTED]>
On 8/7/07, Clebert Suconic <[EMAIL PROTECTED]> wrote: > The solution seems simpler than I thought though... > > After looking at the report again... > [EMAIL PROTECTED] > > ClassConverter probably has a reference to Class... I thought this was > a reflection object. > > It should be WeakReference<Class>. Yes it does (thru' AbstractConveter which it extends) - I can remove that reference completely by just making the getDefaultType() method abstract and having each implementation implement it. > And... inspect your code for any other reflection usages. OK when I get back I was going to have a play with JVMTIInterface - looks good. Niall > Niall Pemberton wrote: > > On 8/6/07, Clebert Suconic <[EMAIL PROTECTED]> wrote: > >> I have been investigating WeakHashMaps on BeanUtils 1.8 as part of a > >> investigation on this: > >> > >> http://jira.jboss.com/jira/browse/JBAS-2299 > > > > Thanks for getting back to us so quickly. > > > >> (Which is not actually an issue with JBAS, but an issue when using > >> BeanUtils as part of the classPath). > >> > >> There is a circular reference on the WeakHashMap, The WeakHashMap will > >> have the ClassLoader as the key, and it will have a reference back to > >> the Key from one of the Reflection objects. This doesn't work! (Please.. > >> no discussions about this point.. if you don't believe me, do some > >> testing with simple stuff before discussing this and come back to me > >> only after that) > > > > OK I will. > > > >> [EMAIL PROTECTED] > >> !--- [EMAIL PROTECTED] > >> !--- !--- class sun.reflect.GeneratedConstructorAccessor38 > >> !--- !--- !--- [Ljava.lang.Object;@10800875 > >> !--- !--- !--- !--- [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- class > >> sun.reflect.GeneratedConstructorAccessor38 > >> !--- !--- !--- !--- !--- !--- !--- class java.lang.Class > >> !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [Ljava.util.HashMap$Entry;@28236766 > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> [EMAIL PROTECTED] > >> !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- !--- > >> !--- [EMAIL PROTECTED] > >> !---!---!---!---!---!---!---!---!---!---!---!---!---!---!---!--- > >> FieldReference private java.lang.Object > >> [EMAIL PROTECTED] > >> Detail > > > > I'm not familiar with JBoss's JVMTIInterface or its output - and it > > seems to be somewhat messed up in posting here - so I've (hopefully) > > cleaned it up and re-posted in a Jira ticket I've opened for this > > here: > > > > https://issues.apache.org/jira/browse/BEANUTILS-291 > > > >> I don't know if I'm preaching to the choir, but just in case this is new > >> information to someone... you should aways keep Reflection referenced as > >> SoftReferences (if you really have to). Reflection is aways a new object > >> so a WeakReference is too weak. > > > > Preach away - I have no great knowledge of this stuff. > > > >> On JBossSerialization I have solved this using an interesting way. I > >> called it PersistentReference. I'm using SoftReferences, and keeping the > >> information to recreate it case the SoftReference is cleared: > >> > >> http://fisheye.jboss.org/browse/JBoss/jboss-serialization/src/org/jboss/serial/references/PersistentReference.java?r=1.3 > >> > >> > >> And also... you guys should write a testcase to validate if the Caching > >> is being cleared. (I don't know if you have one). > >> > >> http://anonsvn.jboss.org/repos/jbossserialization/trunk/tests/org/jboss/serial/memory/MemoryLeakTestCase.java > >> > >> You don't need to use the jboss-profiler API for this.. just create a > >> WeakReference to a new ClassLoader, and validate if it was released at > >> the end after some exercizing some code on this caching. You will > >> probably need to fill your memory almost to 100% on the test as > >> SoftReference are only gone when the memory is low. > > > > Unfortunately I'm away on holiday soon for 3 weeks (12th August to 2nd > > September) - so unless someone else picks this up - ii don't have time > > to look at this until after that. Do you mind if we move the > > discussion over to that Jira ticket I opened though? > > > > Niall > > > >> Clebert Suconic > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
