Hi Serguei,
this fix could possibly finally solve the long standing debugger
problem! Thanks!
Is it possible to backport the fix into older jdk versions?
Thanks,
Egor
On 27.05.2026 0:52, Serguei Spitsyn wrote:
On Thu, 20 Nov 2025 02:24:52 GMT, Serguei Spitsyn <[email protected]> wrote:
This change fixes a long standing performance issue related to the debugger
single stepping that is using JVMTI `FramePop` events as a part of step over
handling. The performance issue is that the target thread continues its
execution in very slow `interp-only` mode in a context of frame marked for
`FramePop` notification with the JVMTI `NotifyFramePop`. It includes other
method calls recursively upon a return from the frame.
This fix is to avoid enforcing the `interp-only` execution mode for threads when
`FramePop` events are enabled with the JVMTI `SetEventNotificationMode()`.
Instead, the target frame has been deoptimized and kept interpreted by disabling
`OSR` optimization by the function
`InterpreterRuntime::frequency_counter_overflow_inner()`. (Big thanks to @fisk for
this suggestion!) Additionally, some tweaks are applied in several places where
the `java_thread->is_interp_only_mode()` is checked.
The other details will be provided in the first PR request comment.
Testing:
- test `serviceability/jvmti/vthread/ThreadStateTest` was updated to provide
some extra test coverage
- submitted mach5 tiers 1-6
- [x] I confirm that I make this contribution in accordance with the [OpenJDK
Interim AI Policy](https://openjdk.org/legal/ai).
This pull request has now been integrated.
Changeset: 7da24777
Author: Serguei Spitsyn <[email protected]>
URL:
https://git.openjdk.org/jdk/commit/7da2477700a976e628d0cd18daa3e1e6d959a463
Stats: 500 lines in 28 files changed: 390 ins; 34 del; 76 mod
6960970: Debugger very slow during stepping
Co-authored-by: Patricio Chilano Mateo <[email protected]>
Reviewed-by: lmesnik, pchilanomate
-------------
PR: https://git.openjdk.org/jdk/pull/28407
