[FELIX-4638] Event Admin - Less locking on event handler timing

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: eventadmin-1.4.4
• Component/s: Event Admin
• Assignee: Carsten Ziegeler
• Reporter: Bob Paulin
• Created: 15/Sep/14 13:30
• Updated: 10/Aug/15 06:59
• Resolved: 29/Sep/14 07:58

Description

The locking that is done for the blacklist timing seems to degrade performance significantly Felix is under stress with multiple firing handler callbacks for each event. I'd like to discuss an alternative approach with less locking that still guarantees proper event ordering per the OSGi spec. Basically instead of using the CyclicBarriers (Rendezvous) on a per handler basis we could use a count down latch to only await after all handlers are complete. Then instead of using a stopwatch based timer the JMX Current Thread Cpu Time which counts CPU time for the application code and any IO performed on it's behalf filtering out time context switching between threads to provide proper blacklisting.

Here are my test results.

Baseline(Event Admin 1.4.2):
15 Threads
100000 Async Events per Thread
7 Active Handlers per Event

For a total of 10500000 Handler Events Executed in 40000 - 45000ms

With the same parameters above but a CountDownLatch I see the execution time drop to around 25000ms. The improvement is noticeable because the stress test includes 7 active handlers per event. The improvement is less noticeable with applications that only register one or 2 handlers for an active event such as in the PerformanceTestIT. Thoughts on changing how this locking occurs? Concerns with using the JMX timings?