[jdk21u-dev] RFR: 8350285: Shenandoah: Regression caused by ShenandoahLock under extreme contention

[Goetz Lindenmaier]

On Mon, 30 Jun 2025 21:03:48 GMT, Daniel Huang <duke at openjdk.org> wrote:

> Backport for ShenandoahLock performance regression issue. The fix involves sleeping for a very short duration every 3 yields, with the number of yields picked through manual testing.
> 
> Clean backport, ran GHA sanity checks and locally tested `tier1`, `tier2`, and `hotspot_gc_shenandoah`. `test/jdk/java/nio/channels/FileChannel/directio/DirectIOTest.java` sometimes fails locally, but it also sometimes failed before the backport.
> `test/jdk/java/nio/channels/DatagramChannel/SendReceiveMaxSize.java` fails locally, but it also fails locally before the backport.

Hi @dtmhuang 
Besides running the tier tests, can you please run some large applications that cause contention on the problematic code?

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PR Comment: https://git.openjdk.org/jdk21u-dev/pull/1933#issuecomment-3027900487