On Fri, 22 May 2026 09:47:16 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). > > Serguei Spitsyn has updated the pull request incrementally with one > additional commit since the last revision: > > review: 1. Add asserts, rem comment 2. Remove can_generate_frame_pop_events > from can_generate_interpreter_events It seems that the first frame is still interpreted (i.e., `foo()`). And inner frames aren't. The following sample demonstrates it: class test { public static void main(String[] args) { int x = foo(); System.out.println(x); } static int foo() { return foo2(); } static int foo2() { long start = System.currentTimeMillis(); int a = 1; for (int i = 0; i < 100_000_000; i++) { a = increment(a); } System.out.println("It took " + (System.currentTimeMillis() - start) + "ms"); return a; } private static int increment(int a) { return a + 1; } } jdb runs fast now: Breakpoint hit: "thread=main", test.main(), line=3 bci=0 3 int x = foo(); main[1] next > It took 3ms ------------- PR Comment: https://git.openjdk.org/jdk/pull/28407#issuecomment-4845862823
