PersistenceManagerFactory getPersistenceManager() hangs up in case there is active transaction.

[slavap]

PersistenceManagerFactory getPersistenceManager() hangs up in case there is active transaction.

[tzaeschke]

Thanks a lot. I'm a bit busy at the moment, I'll have a look next week.

[tzaeschke]

Hi, if I understand correctly, this is a fix for the test that you provided.
Or are you seeing a problem with ZooDB? If yes, could you describe the error and tell me which branch you tested? At the moment the test runs just fine for me.

[slavap]

Hi,
No, it's not a fix for the test.
If you change code to the first version, test won't work, and just hangs up.
The second version (currently in the code) works just fine, that's why test works for you.
Both versions are semantically equal of course.
I'm using master branch, let me know if you need additional info.

[tzaeschke]

The problem is that ZooDB currently uses one write-lock to lock the whole server. That means that there can be only one open transaction at any time. I had the same problem in some of the Concurrent-Schema tests. As a workaround, I implemented a function DiskAccessOneFile.allowReadConcurrency(true); (place it before tx.begin()). This causes the server to use only a read-lock, but it is not threadsafe and should only be used if no more than one thread is controlling the different transactions.
Thanks for reporting this and for the fix to the concurrency test.

[tzaeschke]

Fixed. In ConcurrencyTest I had to change the startConcurrentTransfer method to deal with OptimisticVerification Exceptions:

           public void run()
            {
                LOG.debug(">> Starting thread " + transferId + " in pm=" + pm);
                synchronized (lock)
                {
                    lock.notifyAll();
                }

                boolean success = false;
                do {
	                try {
	                    pm.currentTransaction().begin();
	                    Transfer t = (Transfer) pm.getObjectById(transferId, true);
	                	performTransfer(t);
	                	success = true;
	                } catch (JDOOptimisticVerificationException e) {
	                	success = false;
	                	System.out.println("Transaction failed, retrying...");
	                } finally {
	                	if (success) {
	                        closePm(pm);
	                	}
	                }
                } while (!success);
                LOG.debug(">> Completed thread " + transferId + " in pm=" + pm);
            }