From 551cd03b99feb34d98703b7d04571f92f83f2471 Mon Sep 17 00:00:00 2001
From: Xiaolong Peng <xpeng@openjdk.org>
Date: Mon, 13 Oct 2025 15:03:01 +0000
Subject: [PATCH] 8369611: Remove safepoint synchronization from
 ParallelScavengeHeap and SerialHeap

Reviewed-by: kbarrett, ayang, shade, tschatzl
---
 .../share/gc/parallel/parallelScavengeHeap.cpp       | 11 -----------
 .../share/gc/parallel/parallelScavengeHeap.hpp       |  3 ---
 src/hotspot/share/gc/serial/serialHeap.cpp           | 12 ------------
 src/hotspot/share/gc/serial/serialHeap.hpp           |  3 ---
 4 files changed, 29 deletions(-)

diff --git a/src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp b/src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp
index c3b0ec0b1ad..cbea75879ae 100644
--- a/src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp
+++ b/src/hotspot/share/gc/parallel/parallelScavengeHeap.cpp
@@ -152,17 +152,6 @@ void ParallelScavengeHeap::initialize_serviceability() {
 
 }
 
-void ParallelScavengeHeap::safepoint_synchronize_begin() {
-  if (UseStringDeduplication) {
-    SuspendibleThreadSet::synchronize();
-  }
-}
-
-void ParallelScavengeHeap::safepoint_synchronize_end() {
-  if (UseStringDeduplication) {
-    SuspendibleThreadSet::desynchronize();
-  }
-}
 class PSIsScavengable : public BoolObjectClosure {
   bool do_object_b(oop obj) {
     return ParallelScavengeHeap::heap()->is_in_young(obj);
diff --git a/src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp b/src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp
index fea827430ca..bf777bda29e 100644
--- a/src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp
+++ b/src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp
@@ -159,9 +159,6 @@ public:
   // Returns JNI_OK on success
   jint initialize() override;
 
-  void safepoint_synchronize_begin() override;
-  void safepoint_synchronize_end() override;
-
   void post_initialize() override;
   void update_counters();
 
diff --git a/src/hotspot/share/gc/serial/serialHeap.cpp b/src/hotspot/share/gc/serial/serialHeap.cpp
index 3442dc4c907..3ab88da4633 100644
--- a/src/hotspot/share/gc/serial/serialHeap.cpp
+++ b/src/hotspot/share/gc/serial/serialHeap.cpp
@@ -144,18 +144,6 @@ GrowableArray<MemoryPool*> SerialHeap::memory_pools() {
   return memory_pools;
 }
 
-void SerialHeap::safepoint_synchronize_begin() {
-  if (UseStringDeduplication) {
-    SuspendibleThreadSet::synchronize();
-  }
-}
-
-void SerialHeap::safepoint_synchronize_end() {
-  if (UseStringDeduplication) {
-    SuspendibleThreadSet::desynchronize();
-  }
-}
-
 HeapWord* SerialHeap::allocate_loaded_archive_space(size_t word_size) {
   MutexLocker ml(Heap_lock);
   return old_gen()->allocate(word_size);
diff --git a/src/hotspot/share/gc/serial/serialHeap.hpp b/src/hotspot/share/gc/serial/serialHeap.hpp
index 388da13b1b0..27053b4cc81 100644
--- a/src/hotspot/share/gc/serial/serialHeap.hpp
+++ b/src/hotspot/share/gc/serial/serialHeap.hpp
@@ -258,9 +258,6 @@ public:
   void scan_evacuated_objs(YoungGenScanClosure* young_cl,
                            OldGenScanClosure* old_cl);
 
-  void safepoint_synchronize_begin() override;
-  void safepoint_synchronize_end() override;
-
   // Support for loading objects from CDS archive into the heap
   bool can_load_archived_objects() const override { return true; }
   HeapWord* allocate_loaded_archive_space(size_t size) override;