What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

Question

Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outli

Answer 1

Update: V7 - Busy Wait that reverts to Wait/Notify

After some playing around with V6 it turns out that the busy waits obscure the real hotspots of the application a bit when profiling. Plus, the fan on the system keeps going into overdrive even if no work items are being processed. So a further improvement was to busy wait for work items for a fixed amount of time (say, about 2 milliseconds) and then to revert to a "nicer" wait()/notify() combination. The worker threads simply publish their current wait mode to the main thread via an atomic boolean that indicates whether they are busy waiting (and hence just need a work item to be set) or whether they expect a call to notify() because they are in wait().

Another improvement that turned out to be rather straight-forward was to let threads that have completed their primary work item repeatedly invoke a client-supplied callback while they are waiting for the other threads to complete their primary work items. That way, the wait time (which happens because threads are bound to get slightly different work loads) does not need to be completely lost to the app.

I am still very interested in hearing from other users that encountered a similar use case.