On Tue, 8 Sep 2026 09:34:09 GMT, Fredrik Bredberg <[email protected]> wrote:
> This PR removes displaced-mark related code from the Serviceability Agent, > which has become obsolete since > [JDK-8389325](https://bugs.openjdk.org/browse/JDK-8389325) removed the > `UseObjectMonitorTable` flag. > > It also aligns the SA's mark-word related `printOn()` and `hasMonitor()` > functions to their respective C++ functions, `markWord::print_on()` and > `markWord::has_monitor()`. > > Because the displaced-mark related code was removed, the > `identityHashValueFor()` has been reduced to one line, just returning the > hash code directly from the object's mark-word. > > Passes tier1-3 on supported platforms. I also successfully ran > `TEST="hotspot/jtreg/serviceability/sa"` on my local machine. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). Looks good, just some nits, and potentially some more dead locking code we could remove. src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/Mark.java line 136: > 134: public boolean isBeingInflated() { > 135: return (value() == 0); > 136: } I wonder if we should just remove this as well. It is old legacy locking displaced markWord related. Suggestion: src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/Mark.java line 151: > 149: } > 150: public boolean hasMonitor() { > 151: // Align SA’s decoding with markWord::has_monitor(). Seems like an unnecessary comment to have in the code. I would have expected a comment if for some reason we did not align the SA's mirror implementation with the HotSpot code. _(Also that is an exotic apostrophe `’` vs `'`)_ Suggestion: src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/ObjectSynchronizer.java line 30: > 28: > 29: import sun.jvm.hotspot.oops.*; > 30: import sun.jvm.hotspot.utilities.*; Maybe this are imported "just cause". But the last use of the import was removed with the `Asserts` removal. Suggestion: ------------- Changes requested by aboldtch (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/32758#pullrequestreview-5150279351 PR Review Comment: https://git.openjdk.org/jdk/pull/32758#discussion_r3965097422 PR Review Comment: https://git.openjdk.org/jdk/pull/32758#discussion_r3965084808 PR Review Comment: https://git.openjdk.org/jdk/pull/32758#discussion_r3965152513
