From 99c299f0985c8be63b9b60e589db520d83fd8033 Mon Sep 17 00:00:00 2001
From: Thomas Schatzl <tschatzl@openjdk.org>
Date: Mon, 14 Jul 2025 09:39:06 +0000
Subject: [PATCH] 8361706: Parallel weak klass link cleaning does not clean out
 previous klasses

Reviewed-by: eosterlund, coleenp
---
 .../share/gc/shared/parallelCleaning.cpp        |  2 +-
 .../share/gc/shared/parallelCleaning.hpp        |  4 ----
 src/hotspot/share/oops/klass.cpp                | 17 ++++++++++-------
 src/hotspot/share/oops/klass.hpp                |  3 +++
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/hotspot/share/gc/shared/parallelCleaning.cpp b/src/hotspot/share/gc/shared/parallelCleaning.cpp
index 4708df4d3e5..0cba1f8e166 100644
--- a/src/hotspot/share/gc/shared/parallelCleaning.cpp
+++ b/src/hotspot/share/gc/shared/parallelCleaning.cpp
@@ -128,6 +128,6 @@ void KlassCleaningTask::work() {
   // All workers will help cleaning the classes,
   InstanceKlass* klass;
   while ((klass = claim_next_klass()) != nullptr) {
-    clean_klass(klass);
+    Klass::clean_weak_instanceklass_links(klass);
   }
 }
diff --git a/src/hotspot/share/gc/shared/parallelCleaning.hpp b/src/hotspot/share/gc/shared/parallelCleaning.hpp
index a15326f1b85..6b16894954c 100644
--- a/src/hotspot/share/gc/shared/parallelCleaning.hpp
+++ b/src/hotspot/share/gc/shared/parallelCleaning.hpp
@@ -66,10 +66,6 @@ private:
 
 public:
 
-  void clean_klass(InstanceKlass* ik) {
-    ik->clean_weak_instanceklass_links();
-  }
-
   void work();
 };
 
diff --git a/src/hotspot/share/oops/klass.cpp b/src/hotspot/share/oops/klass.cpp
index 958e1f61351..41ab8e325ab 100644
--- a/src/hotspot/share/oops/klass.cpp
+++ b/src/hotspot/share/oops/klass.cpp
@@ -749,17 +749,20 @@ void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_kla
     // Clean the implementors list and method data.
     if (clean_alive_klasses && current->is_instance_klass()) {
       InstanceKlass* ik = InstanceKlass::cast(current);
-      ik->clean_weak_instanceklass_links();
-
-      // JVMTI RedefineClasses creates previous versions that are not in
-      // the class hierarchy, so process them here.
-      while ((ik = ik->previous_versions()) != nullptr) {
-        ik->clean_weak_instanceklass_links();
-      }
+      clean_weak_instanceklass_links(ik);
     }
   }
 }
 
+void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) {
+  ik->clean_weak_instanceklass_links();
+  // JVMTI RedefineClasses creates previous versions that are not in
+  // the class hierarchy, so process them here.
+  while ((ik = ik->previous_versions()) != nullptr) {
+    ik->clean_weak_instanceklass_links();
+  }
+}
+
 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
   if (log_is_enabled(Trace, aot)) {
     ResourceMark rm;
diff --git a/src/hotspot/share/oops/klass.hpp b/src/hotspot/share/oops/klass.hpp
index 58112b732b9..18b8b5885a3 100644
--- a/src/hotspot/share/oops/klass.hpp
+++ b/src/hotspot/share/oops/klass.hpp
@@ -734,7 +734,10 @@ public:
 
   void clean_subklass();
 
+  // Clean out unnecessary weak klass links from the whole klass hierarchy.
   static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
+  // Clean out unnecessary weak klass links from the given InstanceKlass.
+  static void clean_weak_instanceklass_links(InstanceKlass* ik);
 
   // Return self, except for abstract classes with exactly 1
   // implementor.  Then return the 1 concrete implementation.