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javahazelcastxa

XA transaction involving JMS, Database and Hazelcast distributed collection

One of our application is expected to have a significant load increase soon and I am in the process of evaluating Hazelcast distributed collections to help us eliminate some existing database bottlenecks.

Multiple instances of our application are running on a bunch of different hosts for horizontal scaling. Different modules of the application get deployed to multiple Webshere Application Servers to spread the load to multiple JVMs. A typical work flow consist in:

  1. A message gets pushed to an MDB from an Webshere MQ queue
  2. The MDB parses the message and saves it to the database
  3. The MDB extracts from the message a special key identifying related messages, and inserts that key into a special locking table so once such a key is picked up by a node it will process all related messages on that node. Processing all related messages in sequence is crucial to our application. This table is one of the things we want to replace with a hazelcast blocking queue.
  4. The same MDB sends a notification in a Webshere MQ topic informing the other JVMs that work arrived for further processing. This topic we consider replacing with a Hazelcast topic but this is optional

All the above flow happens in the same XA transaction so once the other JVMs receive the notification it is certain that the locking table entry is there available for pick up.

The receiving JVMs once they gets the notification will jump on the locking table trying to lock a key and process all the messages belonging to that key. There is a constant flow of messages so there are always keys ready for pick up by all running JVMs.

We noticed part of our stress tests that because of the multiple threads trying to lock keys at the same time the database starts being under an increasing pressure affecting the overall performance of our application.

There are a few such semaphore tables controlling the in sequence processing and this is what we consider moving to an in memory data grid.

The above is pretty much our story. In theory it seems like a good idea and I hope to achieve a performance increase not necessarily because reducing network traffic as this will happen anyway but at least by spreading the pressure on more than one resource.

I tried to google about how to set up an XA transnational context in which JMS, DB and Hazelcast collections take part. Unfortunately Hazelcast documentation about XA is just a few rows of code and nothing more. I am sure I am not the only one facing this problem and I hope for some inputs here. No need for a working solution, just a link to a good example or some more how to tips documentation to get me moving would be enough.

Thanks u in advance

Solution

  • If you use JTXA and the Hazelcast Resource Adapter (github.com/hazelcast/hazelcast-ra), Hazelcast will be part of the overall JTXA transaction which can include any type of transaction.