Hi,

As you may know we have been running load tests for the last 2 weeks. The numbers that we are getting are really awesome so I wanted to share with you some practices and optimizations we done in order to improve scalability of our next Wildfire version.

• Out of the box DB connection pool has a min size of 5. This was the first bottleneck we found. The min and max size was set to 100.

• Cache size is also a key factor to get good performance. A small cache size or low effectiveness implies more db queries. The main cache that we needed to increase was the Roster cache. To hold the roster of 25K users that contain 20 contacts each we needed a 48MB cache.

• Offline timestamp is now stored in its own table (and uses a new Cache). Before it was being stored as a user property and it was a big bottleneck when users were coming online or offline.

• Move as many db operations (INSERT, UPDATE) to run as batch processes. This will improve overall performance and reduce number of locks.

• Use MINA to handle Connection Managers from Wildfire. MINA is a SEDA solution so overall performance will be greatly improved. MINA uses thread pools, queues and a Thread for sending packets.

• MINA also supports a throttling filter that could be used to reduce incoming traffic when Wildfire has reached 100% of its capacity.

• Optimized Cache#calculateSize to consider Strings and avoid serializing Strings to estimate their size.

• Optimization: do not load User when not needed. In particular, do not validate if a user exists after it was successfully authenticated.

• Optimization: avoid creating of DOM objects in CMs. Just pass the received Strings to Wildfire. This was a huge optimization.

• Optimization: reduce number of parser instances in CMs. One per working thread instead of one per connection. This was a huge optimization.

• Avoid reflection if possible. Reflection in Java is not that optimized. In particular, we replaced usage of reflection while executing a DB command with an IF statement.

Regards,

  -- Gato