Integrated: 8292240: CarrierThread.blocking not reset when spare not activated

[Alan Bateman]

On Thu, 11 Aug 2022 16:11:02 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> Some blocking operations that pin a virtual thread to its carrier will compensate by activating a spare carrier (essentially managed blocker). This is done by wrapping the operation in a Blocker begin/end. This code is not correct for the case that a spare cannot be activated (e.g. already at the max of 256 carrier threads). When that happens, the carrier thread's "blocking" flag, used to detect reentrancy, is not reset when the blocking operation is done. The result is that subsequent blocking operations by virtual threads on this carrier thread will not attempt to activate a spare.
> 
> The test runs with parallelism=1 and maxPoolSize=2 in order to make it easier to create the conditions for this bug.

This pull request has now been integrated.

Changeset: 68da02c7
Author:    Alan Bateman <alanb at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/68da02c7b536799ccca49e889c22f3e9a2691fb7
Stats:     154 lines in 2 files changed: 148 ins; 0 del; 6 mod

8292240: CarrierThread.blocking not reset when spare not activated

Reviewed-by: dfuchs

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PR: https://git.openjdk.org/jdk/pull/9841