Integrated: 8335289: GenShen: Whitebox breakpoint GC requests may cause assertions

[William Kemper]

On Thu, 27 Jun 2024 23:02:41 GMT, William Kemper <wkemper at openjdk.org> wrote:

> When a test requests a concurrent GC breakpoint, the calling thread arranges for itself to block until the concurrent GC thread notifies it that the GC has reached the requested breakpoint (phase). The code that handles the whitebox breakpoint request should therefore not block the caller. An attempt was made to do this, but the request just has the caller thread run in a busy loop without waiting. What's more, this loop resets the requested gc cause on every iteration, which may lead to gc cycles with a wb_breakpoint cause, but no breakpoint set - which violates assertions.

This pull request has now been integrated.

Changeset: 71182e24
Author:    William Kemper <wkemper at openjdk.org>
URL:       https://git.openjdk.org/shenandoah/commit/71182e240ce4f4a6e3a8773f61be6b091e2d65e9
Stats:     26 lines in 2 files changed: 20 ins; 4 del; 2 mod

8335289: GenShen: Whitebox breakpoint GC requests may cause assertions

Reviewed-by: kdnilsen

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PR: https://git.openjdk.org/shenandoah/pull/453