FJP.CommonPool and VM shutdown

[Doug Lea]

On 01/01/13 13:20, Brian Goetz wrote:
> I can't get too worked up about this failure mode, so I'll revert to bikeshed
> mode: a nicer name would have "await" in the name.

I made a small adjustment to make these more consistent.
While awaitTermination and awaitQuiescence remain unchanged
from version I pasted, and have the same form of requiring a
timeout argument, the untimed version is now only available
in its previous form of ForkJoinTask.helpQuiesce. The implementation
just so happens to relay to awaitQuiescence without a timeout.
Even though they are basically the same, the usage contexts
differ enough to separate them in this way.

Minor updates to javadocs at:
http://gee.cs.oswego.edu/dl/jsr166/dist/docs/java/util/concurrent/ForkJoinPool.html

(Currently, awaitQuiescence never actually blocks but only tries
helping until quiescent. There are a few cases where you might
want it to block, as when the last ongoing task before
quiescence is itself blocking. It is (barely) possible
to trap/detect this, so this might change someday.)

-Doug

>
> On 1/1/2013 6:55 AM, Doug Lea wrote:
>>
>> While writing some CompletableFuture test code, I
>> realized that there's a potential unhappy surprise
>> lurking in code of the form:
>>
>> class X {
>>    public static void main(String[] args) {
>>       new ComputationUsingCommonPool(...).fork();
>>    }
>> }
>>
>>
>> Because the common pool uses daemon threads, it is
>> OK for the VM to shutdown immediately after the fork().
>>