Terracotta Discussion Forums

Hi,
I am using Terracotta 3.4.1 for my product and I am sharing a LinkedBlockingQueue as a DSO. Problem is when I tried to read the objects of this queue from other JVM(which is obviously terracotta client), I am getting class cast exception. "java.lang.ClassCastException: com.tc.object.ObjectID" We are just trying to shift to 3.4.1 and this code is running fine in terracotta 2.7.3.

Any hints?

Thanks
Ankush

The full stacktrace is required.

This is the full stack trace and its not of much help too...

java.lang.ClassCastException: com.tc.object.ObjectID
at net.deepvalue.alert.AlertEngineService.run(AlertEngineService.java:121)
at java.lang.Thread.run(Thread.java:595)

Hmm, that sure smells like a bug. ObjectID is our internal type for a handle/pointer to clustered object. It should be resolved to a real object before it ever escapes a method like take() or poll() on an LBQ

Any chance you have something that reproduces the issue? That would be the easiest way to debug this :-)

Not that I know what I'll do with this information but what methods do you use for reading/writing this queue? What is the bound? Does the problem go away if you use a larger or smaller capacity?

I also observed the same exception when using the .toArray() and .iterator() methods on Queue obtained by toolkit.getBlockingQueue():
The exception only occured for elements that had been in the queue before the client was started.

Tested with terracotta 3.4.0_1 and 3.4.1.

Attached is a test class showing the issue:

1. Start local TC server
2. Run all the tests in the class
=> all tests succeed
3. Run all the tests again (without restarting the tc server)
=> testBlockingQueueToArray, testBlockingQueueToArrayNoneDefaultCapacity and testBlockingQueueIterator FAIL

I can see that this issue has been fixed: http://jira.terracotta.org/jira/browse/CDV-1580

Can you tell me if it was already released?

I am checking with Terracotta 3.5.2, 3.5.3 and terracotta-toolkit-1.3-runtime 3.3.0 and I still can reproduce this bug.

Best,
Maciej

CDV-1580 is only fixed in our upcoming 3.6.0 release unfortunately.

Thanks for the information. It's not critical for us so we can wait, but it could be nice to preview the queue from maintenance point of view.

In the CDV-1580 ticket it is mentioned: "Feature failure (but usable), workaround available". I couldn't find any Terracota Toolkit API to fetch the object using ObjectID, so does any workaround exist?

Best,
Maciej

Sorry that "serverity" field is very often not properly used. There is no workaround that I know of