On Tue, 25 Nov 2025 02:25:02 GMT, Chris Plummer <[email protected]> wrote:
> Don't enabled VIRTUAL_THREAD_START/END events unless absolutely necessary.
> Solves performance issues when trying to debug apps that create a lot of
> virtual threads. Details in first comment.
>
> With these changes the Skynet benchmark no longer shows any slowdown when
> launching with debugging enabled or when attaching the debugger.
>
> Tested with all tier2, tier3, tier5, and tier6 CI testing (with filters to
> only run svc tests).
src/jdk.jdwp.agent/share/native/libjdwp/eventFilter.c line 1444:
> 1442: } else {
> 1443: error = threadControl_setEventMode(JVMTI_DISABLE,
> EI_VIRTUAL_THREAD_END, thread);
> 1444: }
Q: Why is the `THREAD_START` event disabled globally (for all threads) but the
`THREAD_END` event is disabled for specific thread?
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PR Review Comment: https://git.openjdk.org/jdk/pull/28485#discussion_r2559181531
