[ http://issues.apache.org/jira/browse/AXIS-935?page=comments#action_61741 ] Catalin Grigoroscuta commented on AXIS-935: -------------------------------------------
You are right, this is a potential problem with all ThreadLocalS. Personally, I belive that relying strictly on ThreadLocalS is a bad programming technique (except for a few situation, like transaction context, etc), and when ThreadLocalS are used it must be done in try ... finally blocks (either explicit, or document the methods that create them, so that the caller knows how to use them correctly). For AXIS, I would be very happy with the proposed solution, as for the moment the only solution I quickly hacked is to record all thread locals as they are created by AXIS, and to clear them all when the app is shut down. Thought, doesn't this programming style remind you of C programming, where you must correctly pair the malloc/free calls? > Using ThreadLocal Call objects in a servlet memory leak both on client and > server side > -------------------------------------------------------------------------------------- > > Key: AXIS-935 > URL: http://issues.apache.org/jira/browse/AXIS-935 > Project: Axis > Type: Bug > Components: Basic Architecture > Versions: 1.1rc2 > Environment: Operating System: All > Platform: All > Reporter: Jennifer Jackson > > I discovered using Axis in tomcat causes a memory leak. > It seems using threadlocal in the classes causes a memory leak for each Call > that is created. Threadlocal sticks around until the calling thread dies, > and > since tomcat keeps threads alive to answer new calls, the threadlocal data > never goes away. The Call object gets stuck in the threadlocal data, which > contains the entire soap response and all objects. This is a BIG memory > leak. > I initially cleared it by forcing all Call objects to clean their member vars > after I was done with a call, then I realized the source was from the thread > local class. Here is some info I found about threadlocal: > This is stated in the Sun Javadocs for ThreadLocal: > Each thread holds an implicit reference to its copy of a > ThreadLocal as long as the thread is alive and the > ThreadLocal object is accessible; after a thread goes > away, all of its copies of ThreadLocal variables are > subject to garbage collection (unless other references > to these copies exist). > So, this means that ANY APPLICATION that uses PreparedStatements in a thread > that 1) either does a lot of PreparedStatements or 2) never dies (i.e., a > main thread) will ALWAYS eventually have an out of memory error. Simply put, > this is a MEMORY LEAK. I imagine that the leak is very small, the > ThreadLocal object only contains one member variable, maybe 64 bytes or less > (depending on the VM implementation). So, our 60,000 PreparedStatements of 2 > ThreadLocals each times 64 bytes (my wild guess) is 7.5MB. > Ideas? I've never used threadlocal myself so this is new to me. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - If you want more information on JIRA, or have a bug to report see: http://www.atlassian.com/software/jira
