[jboss-user] [JBossCache] - Re: Problem with concurent put/remove operation.

[jacek187]

impy core on 1.4.1 - described in http://www.jboss.com/index.html?module=bb&op=viewtopic&t=116337 forum thread
I have just tested core on 2.0.0. GA - and exception was ... timeout.

stack:
org.jboss.cache.lock.TimeoutException: failure acquiring lock: fqn=/a/b/c/d, caller=GlobalTransaction::4, lock=write owner=GlobalTransaction::3 (activeReaders=0, activeWriter=Thread[Thread-2,5,main], waitingReaders=0, waitingWriters=0, waitingUpgrader=0)
	at org.jboss.cache.lock.IdentityLock.acquire(IdentityLock.java:528)
	at org.jboss.cache.interceptors.PessimisticLockInterceptor$LockManager.acquire(PessimisticLockInterceptor.java:579)
	at org.jboss.cache.interceptors.PessimisticLockInterceptor.acquireNodeLock(PessimisticLockInterceptor.java:393)
	at org.jboss.cache.interceptors.PessimisticLockInterceptor.lock(PessimisticLockInterceptor.java:329)
	at org.jboss.cache.interceptors.PessimisticLockInterceptor.invoke(PessimisticLockInterceptor.java:187)
	at org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:76)
	at org.jboss.cache.interceptors.NotificationInterceptor.invoke(NotificationInterceptor.java:32)
(...)
main loop:

  | 				for (int x = 0; x < 1000; x++) {
  | 					tm.begin();
  | 					if (remove) {
  | 						cache.remove("/a/b/c/d");
  | 						cache.remove("/a");
  | 					} else {
  | 						cache.put("/a/b/c/d", "key","text" + x);
  | 					}
  | 					tm.commit();
  | 					Thread.sleep(1);
  | 				}
  | 

one thread is putting key-value pair into /a/b/c/d node and second thread is removing this node.

And now I don't known what is it: just bug or normal situation. 
If this is normal situation - how TimeoutException can be explained? One thread is executing only one operation in one transaction (classical deadlock needs 2 operations in one transaction...)

I need to run many paraller threads, and every thread should modify exactly this same node. Which cache should be used? [I think that every cache (pojo, core, 1.4.1, 2.0.0 can be used)] Now looks that only PojoCache in version 1.4.1 works correctly in Multithread environment...

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