Hello list readers, I'm running into a memory problem with OJB on a long running server. After a couple of weeks the heap has grown in size from +- 150 MB to over 500 MB. Today I used the "jmap" tool that comes with je JDK to actually dump a heap histogram:
189072640 107 org.apache.ojb.broker.PBStateListener[] 109750848 4572952 java.lang.ref.WeakReference 73035968 4564748 org.apache.ojb.broker.accesslayer.RsIterator$ResourceWrapper 27267184 22219 byte[] 25734504 302777 char[] 7466688 311112 java.lang.String 7442584 57688 * ConstMethodKlass 4159032 57688 * MethodKlass 189 MB is taken up by just 107 PBStateListener arrays! If we add up the majority of WeakReference and RsIterator$ResourceWrapper instances we end up with a leak of more than 300 MB, just about the size of the unexpected heap growth we have been experiencing. After analysing the OJB source code, I found that the PBStateListener management in PersistenceBrokerAbstractImpl might be suspect. The arrays that store the listeners (permanent and temporary) only seem to be able to grow. The "removeListener" method is never actually called, and considering the inefficiency of the algorithms used to add and remove listeners I suspect that these methods where never meant to manage large amounts of active listeners. The "removeAllListeners" method only seem te be called when closing and destroying the PersistenceBrokerImpl instance. The "addListener" method is called on every query though, so the size of the arrays after a couple of weeks does not surprise me. WeakReferences are used to make sure no references to the actual PBStateListener implementors are leaked, but the week references themselves (and the wrappers around them) are never removed, thus causing the PBStateListener arrays to keep growing. If this analysis is correct, I don't understand why nobody else is having this problem. I must be doing something radically different (more stupid?) than most other OJB users. Is there some other way these arrays are supposed to get freed that I'm not using because of a bug in my code? If so could you point me in the right direction where I might begin looking for problems? As you can imagine this is a serious performance problem for us, so I would very much appreciate any help or advice. Regards, Pieter. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
