Shenandoah and JFR

[Bechberger, Johannes]

Hi Aleksey,

I only ever tested it on a 128 core machine (64 CPUs with hyperthreading). It doesn’t seem to fail on my smaller machine, which I currently only have access to, maybe because of the lacking parallelism. I’ll be running it for a while now.

Regards
Johannes

From: shenandoah-dev <shenandoah-dev-retn at openjdk.org> on behalf of Bechberger, Johannes <johannes.bechberger at sap.com>
Date: Tuesday, 25. February 2025 at 06:53
To: Aleksey Shipilev <shipilev at amazon.de>, shenandoah-dev at openjdk.org <shenandoah-dev at openjdk.org>
Subject: Re: Shenandoah and JFR
Hi Aleksey,

I didn’t check JDK 23’s and JDK 21’s head, just the latest released version.
I’m happy to check this later in the day.

Regards
Johannes

From: Aleksey Shipilev <shipilev at amazon.de>
Date: Tuesday, 25. February 2025 at 06:49
To: Bechberger, Johannes <johannes.bechberger at sap.com>, shenandoah-dev at openjdk.org <shenandoah-dev at openjdk.org>
Subject: Re: Shenandoah and JFR
Hi Johannes,

On 24.02.25 20:56, Bechberger, Johannes wrote:
> Thank you. The issue only occurs on Shenandoah, not with any other GC.

Your original Gist says: "This works for the current JDK head, JDK 23 and JDK 21. So I would assume
that it affects all JDKs that include the Shenandoah GC at the moment of writing."

Could you double-check the issue reproduces on JDK 21 for you? I found a bug that affects JDK 25:
  https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.openjdk.org%2Fbrowse%2FJDK-8350580%3FfocusedId%3D14756096%23comment-14756096&data=05%7C02%7Cjohannes.bechberger%40sap.com%7Ce55d97d56615412d279308dd55926b9e%7C42f7676cf455423c82f6dc2d99791af7%7C0%7C0%7C638760809550577176%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=6hSBngvEa%2F0EdqLVwcFZPG5g9zkxMKnFbP0FdOk90%2F4%3D&reserved=0<https://bugs.openjdk.org/browse/JDK-8350580?focusedId=14756096#comment-14756096>

...and my prospective fix resolves JDK 25 crash. But the reproducer runs fine on current jdk21u-dev.

Thanks,
-Aleksey
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