RFR: 8369392: Safepoint sync should suspend GC and Java threads concurrently

[Xiaolong Peng]

On Tue, 28 Oct 2025 06:53:32 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> I don't think this should be done for ZGC. We intentionally perform the lengthy GC syncronization before we start to synchronize the Java thread. With the proposed change the Java threads could end up blocking longer because they now also have to wait for the GC threads to synchronize.

Thanks for the feedback, now I think I know why Kim said it won't help ZGC. The simple solution in PR applies to all GCs, we may still the more sophisticated solution like https://github.com/openjdk/jdk/pull/27739 so we can control the behavior on individual GC if necessary.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/27924#issuecomment-3458606384