8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired #26232

sspitsyn · 2025-07-10T01:12:11Z

The VM option -XX:AllowRedefinitionToAddDeleteMethods was added in JDK 13 as a temporary backward compatibility flag under JDK-8192936 and was immediately marked as Deprecate. The fix is to obsolete this option in JDK 26 and expire in JDK 27.

TBD: Need to submit a related CSR.

There are two concerns which may require some negotiation with the Runtime (@coleenp @dcubed-ojdk @dholmes-ora) and SQE (@lmesnik) teams:

Class redefinition/retransformation can impact lambda expressions which are supported with private methods
Many tests depend on this VM option and are being removed. I'm not sure if it is okay to completely remove those e may want another way to handle this (e.g. problem-listing the impacted tests for now).

Testing:

mach5 tiers 1-6 are good
may need to run mach5 tiers > 6

Progress

Change must be properly reviewed (1 review required, with at least 1 Reviewer)
Change must not contain extraneous whitespace
Commit message must refer to an issue

Issue

JDK-8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired (Bug - P4)

Reviewers

Coleen Phillimore (@coleenp - Reviewer) 🔄 Re-review required (review applies to 833c6169)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/26232/head:pull/26232
$ git checkout pull/26232

Update a local copy of the PR:
$ git checkout pull/26232
$ git pull https://git.openjdk.org/jdk.git pull/26232/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 26232

View PR using the GUI difftool:
$ git pr show -t 26232

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/26232.diff

Using Webrev

Link to Webrev Comment

…obsoleted then expired

bridgekeeper · 2025-07-10T01:13:05Z

👋 Welcome back sspitsyn! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-07-10T01:13:08Z

@sspitsyn This change is no longer ready for integration - check the PR body for details.

openjdk · 2025-07-10T01:13:45Z

@sspitsyn The following labels will be automatically applied to this pull request:

core-libs
hotspot
serviceability

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-07-10T01:17:33Z

Webrevs

dholmes-ora

This involved a lot more code than I had envisaged.

The test situation seems problematic as it suggests to me that we have required functionality (redefine a method containing a lambda expression) that is not possible without the flag. And it seems this flag is also being used in the wild e.g.

https://blog.picnic.nl/embracing-java-17-heres-what-we-learned-69779d95fdf2

As of Java 16, JDK internals are strongly encapsulated by default (JEP 396). These and other changes mean that some dependencies now require additional JVM flags such as --add-opens and -XX:+AllowRedefinitionToAddDeleteMethods to function properly. We updated our shared build system such that teams can configure these flags in a single place, ensuring that test and production runtimes remain in sync.

With more info in reactor/BlockHound#33

So I am quite concerned that this "workaround" has become entrenched.

dholmes-ora · 2025-07-10T07:09:49Z

src/hotspot/share/prims/jvmtiRedefineClasses.cpp

@@ -4114,18 +4050,14 @@ void VM_RedefineClasses::flush_dependent_code() {
  JvmtiExport::set_all_dependencies_are_recorded(true);
 }

-void VM_RedefineClasses::compute_added_deleted_matching_methods() {
+void VM_RedefineClasses::compute_matching_methods() {


I can't see that this method actually still does anything useful. ??

I think it does:

has asserts on added/deleted methods

collects _matching_old_methods and _matching_new_methods

It seems that the _old_methods is same as _matching_old_methods and _new_methods is same as _matching_new_methods. But I do not want to make a deeper refactoring at this point until we have a decision on the full removal of added/deleted methods support. It feels like we may need to keep some support for lambda expression changes in class redefinitions/retransformations.

What this does now is that the redefined class can have matching method names in a different order because of the signature. So this sorts this out. I don't know why we don't sort methods according to name and signature when creating the klass though. That would make this just a method to check that the methods match.

src/hotspot/share/runtime/arguments.cpp

AlanBateman · 2025-07-10T09:09:27Z

/label remove core-libs

openjdk · 2025-07-10T09:09:47Z

@AlanBateman
The core-libs label was successfully removed.

sspitsyn · 2025-07-11T05:26:12Z

So I am quite concerned that this "workaround" has become entrenched.

Thank you for the comments and concern! I'll check what can be done here. Need to investigate it a little bit.

coleenp

It's nice to be able to clean this code out but I also think it's being used. Was there another mechanism that we suggest for instrumenting native methods? And there was code once to prefix native methods so this adding private method mechanism worked.

Edit: I seem to remember TransferNativeFunctionRegistration code was for instrumenting native methods that used adding and deleting static private methods. So maybe this should be removed also as a follow-up?

src/hotspot/share/oops/methodFlags.hpp

coleenp · 2025-07-11T14:59:26Z

src/hotspot/share/prims/jvmtiRedefineClasses.cpp

@@ -4114,18 +4050,14 @@ void VM_RedefineClasses::flush_dependent_code() {
  JvmtiExport::set_all_dependencies_are_recorded(true);
 }

-void VM_RedefineClasses::compute_added_deleted_matching_methods() {
+void VM_RedefineClasses::compute_matching_methods() {


What this does now is that the redefined class can have matching method names in a different order because of the signature. So this sorts this out. I don't know why we don't sort methods according to name and signature when creating the klass though. That would make this just a method to check that the methods match.

sspitsyn · 2025-07-11T18:58:56Z

It's nice to be able to clean this code out but I also think it's being used. Was there another mechanism that we suggest for instrumenting native methods? And there was code once to prefix native methods so this adding private method mechanism worked.

Edit: I seem to remember TransferNativeFunctionRegistration code was for instrumenting native methods that used adding and deleting static private methods. So maybe this should be removed also as a follow-up?

In fact, I have a big doubt we really want to get rid of this approach to instrument native methods calls.
The same doubt is about lambda expressions change support. It feels we need more thinking on this and some kind of consensus on this.

8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be …

a7bceac

…obsoleted then expired

openjdk bot added the rfr Pull request is ready for review label Jul 10, 2025

openjdk bot added serviceability [email protected] hotspot [email protected] core-libs [email protected] labels Jul 10, 2025

corrected one assert message

a835840

dholmes-ora reviewed Jul 10, 2025

View reviewed changes

openjdk bot removed the core-libs [email protected] label Jul 10, 2025

review: keep right order of the obsoleted VM options

833c616

coleenp approved these changes Jul 11, 2025

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label Jul 11, 2025

review: replace RESERVED flag with UNUSED

fc5630c

openjdk bot removed the ready Pull request is ready to be integrated label Jul 11, 2025

Merge

3900252

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired #26232

8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired #26232

sspitsyn commented Jul 10, 2025 •

edited by openjdk bot

Loading

Uh oh!

bridgekeeper bot commented Jul 10, 2025

Uh oh!

openjdk bot commented Jul 10, 2025 •

edited

Loading

Uh oh!

openjdk bot commented Jul 10, 2025

Uh oh!

mlbridge bot commented Jul 10, 2025 •

edited

Loading

Uh oh!

dholmes-ora left a comment •

edited

Loading

Uh oh!

dholmes-ora Jul 10, 2025

Uh oh!

sspitsyn Jul 11, 2025

Uh oh!

coleenp Jul 11, 2025

Uh oh!

Uh oh!

AlanBateman commented Jul 10, 2025

Uh oh!

openjdk bot commented Jul 10, 2025

Uh oh!

sspitsyn commented Jul 11, 2025

Uh oh!

coleenp left a comment •

edited

Loading

Uh oh!

Uh oh!

coleenp Jul 11, 2025

Uh oh!

sspitsyn commented Jul 11, 2025

Uh oh!

Uh oh!

8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired #26232

Are you sure you want to change the base?

8358890: VM option -XX:AllowRedefinitionToAddDeleteMethods should be obsoleted then expired #26232

Conversation

sspitsyn commented Jul 10, 2025 • edited by openjdk bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Progress

Issue

Reviewers

Reviewing

Uh oh!

bridgekeeper bot commented Jul 10, 2025

Uh oh!

openjdk bot commented Jul 10, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

openjdk bot commented Jul 10, 2025

Uh oh!

mlbridge bot commented Jul 10, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Webrevs

Uh oh!

dholmes-ora left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

dholmes-ora Jul 10, 2025

Choose a reason for hiding this comment

Uh oh!

sspitsyn Jul 11, 2025

Choose a reason for hiding this comment

Uh oh!

coleenp Jul 11, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

AlanBateman commented Jul 10, 2025

Uh oh!

openjdk bot commented Jul 10, 2025

Uh oh!

sspitsyn commented Jul 11, 2025

Uh oh!

coleenp left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

coleenp Jul 11, 2025

Choose a reason for hiding this comment

Uh oh!

sspitsyn commented Jul 11, 2025

Uh oh!

Uh oh!

sspitsyn commented Jul 10, 2025 •

edited by openjdk bot

Loading

openjdk bot commented Jul 10, 2025 •

edited

Loading

mlbridge bot commented Jul 10, 2025 •

edited

Loading

dholmes-ora left a comment •

edited

Loading

coleenp left a comment •

edited

Loading