From 36b66e13c8eca8e460bfd6d900f139408aff9d43 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Sj=C3=B6len?= <jsjolen@openjdk.org>
Date: Tue, 18 Nov 2025 13:05:57 +0000
Subject: [PATCH] 8371778: Make MallocMemorySummary::_snapshot a DeferredStatic

Reviewed-by: phubner, azafari
---
 src/hotspot/share/nmt/mallocTracker.cpp | 4 ++--
 src/hotspot/share/nmt/mallocTracker.hpp | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/hotspot/share/nmt/mallocTracker.cpp b/src/hotspot/share/nmt/mallocTracker.cpp
index a61a27db25d..2cf5034c0bf 100644
--- a/src/hotspot/share/nmt/mallocTracker.cpp
+++ b/src/hotspot/share/nmt/mallocTracker.cpp
@@ -45,7 +45,7 @@
 #include "utilities/ostream.hpp"
 #include "utilities/vmError.hpp"
 
-MallocMemorySnapshot MallocMemorySummary::_snapshot;
+DeferredStatic<MallocMemorySnapshot> MallocMemorySummary::_snapshot;
 
 void MemoryCounter::update_peak(size_t size, size_t cnt) {
   size_t peak_sz = peak_size();
@@ -101,7 +101,7 @@ void MallocMemorySnapshot::make_adjustment() {
 }
 
 void MallocMemorySummary::initialize() {
-  // Uses placement new operator to initialize static area.
+  _snapshot.initialize();
   MallocLimitHandler::initialize(MallocLimit);
 }
 
diff --git a/src/hotspot/share/nmt/mallocTracker.hpp b/src/hotspot/share/nmt/mallocTracker.hpp
index 0ead41f2411..fc03faf7212 100644
--- a/src/hotspot/share/nmt/mallocTracker.hpp
+++ b/src/hotspot/share/nmt/mallocTracker.hpp
@@ -30,6 +30,7 @@
 #include "nmt/memTag.hpp"
 #include "nmt/nmtCommon.hpp"
 #include "runtime/atomicAccess.hpp"
+#include "utilities/deferredStatic.hpp"
 #include "utilities/nativeCallStack.hpp"
 
 class outputStream;
@@ -204,7 +205,7 @@ class MallocMemorySnapshot {
 class MallocMemorySummary : AllStatic {
  private:
   // Reserve memory for placement of MallocMemorySnapshot object
-  static MallocMemorySnapshot _snapshot;
+  static DeferredStatic<MallocMemorySnapshot> _snapshot;
   static bool _have_limits;
 
   // Called when a total limit break was detected.
@@ -251,7 +252,7 @@ class MallocMemorySummary : AllStatic {
    }
 
   static MallocMemorySnapshot* as_snapshot() {
-    return &_snapshot;
+    return _snapshot.get();
   }
 
   // MallocLimit: returns true if allocating s bytes on f would trigger