[concurrency-interest] open up ForkJoinPool.managedBlock to other pool implementations

Mark Falco mark.falco at gmail.com
Wed Jan 22 21:27:07 EST 2020

I wasn’t so much thing about their potential use in TPE, but in non-JDK pools. The ability to know that your thread is blocked is such a critically useful piece of information and I’d love to have access to it for my own custom pool implementations and I imagine other may as well.

thanks again,


> On Jan 22, 2020, at 7:12 PM, Doug Lea via Concurrency-interest <concurrency-interest at cs.oswego.edu> wrote:
> On 1/22/20 8:34 AM, Mark Falco via Concurrency-interest wrote:
>> With the updates being made to the ForkJoinPool and the wider adoption
>> of ManagedBlocker across the j.u.c blocking classes I'm curious if there
>> would be interest/willingness to open this up for use by other thread
>> pool implementations.  
> I had considered this, but it's not clear how useful it would be.  For
> ThreadPoolExecutors (TPE, the basis of most Executors class factories)
> the action would need to conform to the other tunable settings (core
> threads etc), which invites unexpected problems. The least problematic
> cases are TPEs corresponding to Executors.newFixedThreadPool(n). But
> here, it's usually better to replace these pools with "new
> ForkJoinPool(n)". At one point, we considered replacing the Executors
> factory method to do this. But noticed that are a couple of corner-case
> incompatibilities across TPE and FJP involving interactions of timeouts
> and interrupts. These are not commonly encountered, but we have a lot of
> tests for them, so we know them well. I'll re-investigate whether these
> differences can be removed. If so, we might reconsider redefining
> newFixedThreadPool, or at least adding a usage note that people should
> consider FJP as an alternative.
> -Doug
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