[concurrency-interest] ForkJoinTask.externalAwaitDone() co-operates only with commonPool?

Doug Lea dl at cs.oswego.edu
Mon Feb 6 09:14:56 EST 2017

On 02/06/2017 01:47 AM, kirk at kodewerk.com wrote:
> Hi,
> A while back I sifted through f-j and sorted out a way to instrument
> it with JMX. I am sure that my hack wasn’t the best way to instrument
> f-j but it did give me the information I needed at the time. Given
> the importance of the common thread-pool and f-j I am wondering if it
> might be a good idea to explore a way to add instrumentation so that
> important metrics can be exposed via the Platform MBean server to
> improve observability in the runtime?

What metrics do you have in mind? Are they different than
what you can get by calling fjp.toString (which collects
up the status query methods)? Here's a sample output:

java.util.concurrent.ForkJoinPool at 2ef5e5e3[Running, parallelism = 64, 
size = 64, active = 0, running = 0, steals = 112778, tasks = 0, 
submissions = 0]

In general, rather than linking to JMX etc, j.u.c components
have status query methods summarized in toString methods, that
we hope are easy to connect to any monitoring facility.


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