Approved. Thanks for doing this. On Fri, Aug 29, 2014 at 3:43 AM, Paul Sandoz <paul.sandoz@oracle.com> wrote:

Hi,

Please review fixes by Doug to For/Join to improve thread throttling (e.g. for nested parallel streams). This fix resulted in a lot of internal refactoring and clean up.

In addition a new system property was added "java.util.concurrent.ForkJoinPool.common.maximumSpares" (which i suspect will only very rarely be used), so a CCC will be required:

http://cs.oswego.edu/pipermail/concurrency-interest/2014-July/012838.html

* <li>{@code java.util.concurrent.ForkJoinPool.common.maximumSpares} * - the maximum number of allowed extra threads to maintain target * parallelism (default 256).

https://bugs.openjdk.java.net/browse/JDK-8056248

http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8056248-fj-thread-throttling/we...

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Once this review is complete i think we should also backport to 8u40, and likewise for the CompletableFuture updates (which i forgot to mention in a previously related email).

Both these updates have been soaking in the 166 repo for a month or two. No related test failures were reported for a JPRT run with both patches.

Paul.