Integrated: 8338146: Improve Exchanger performance with VirtualThreads

[Doug Lea]

On Mon, 12 Aug 2024 17:07:42 GMT, Doug Lea <dl at openjdk.org> wrote:

> The Exchanger class uses spin-waits that are hostile to some uses of VirtualThreads. Improving this requires a means of estimating whether there are many VirtualThreads with few carriers, which can be supported by adding a method in class ForkJoinWorkerThread. This enables a reworking of the exchange method, and can also be used to deal with similar issues in LinkedTransferQueue and possibly elsewhere. We leave for now open whether this method (hasKnownQueuedWork) should be public, which would allow users to use it in similar contexts, at the possible expense of revealing too much about current VT implementation

This pull request has now been integrated.

Changeset: ab8071d2
Author:    Doug Lea <dl at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/ab8071d28027ecbf5e8984c30b35fa1c2d934de7
Stats:     423 lines in 3 files changed: 94 ins; 172 del; 157 mod

8338146: Improve Exchanger performance with VirtualThreads

Reviewed-by: alanb

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PR: https://git.openjdk.org/jdk/pull/20554