8379230: JFR: Do not store leak context edge idx in markWord

Reviewed-by: egahlin

src/hotspot/share/jfr/leakprofiler/chains/edgeStore.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,8 +26,10 @@
 #include "jfr/leakprofiler/chains/edgeUtils.hpp"
 #include "jfr/leakprofiler/sampling/objectSample.hpp"
 #include "jfr/leakprofiler/utilities/unifiedOopRef.inline.hpp"
+#include "jfr/recorder/service/jfrOptionSet.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/safepoint.hpp"
+#include "utilities/resizableHashTable.hpp"
 
 StoredEdge::StoredEdge(const Edge* parent, UnifiedOopRef reference) : Edge(parent, reference), _gc_root_id(0), _skip_length(0) {}
 
@@ -216,84 +218,62 @@ bool EdgeStore::put_edges(StoredEdge** previous, const Edge** current, size_t li
   return nullptr == *current;
 }
 
-static GrowableArray<const StoredEdge*>* _leak_context_edges = nullptr;
+typedef ResizeableHashTable<uintptr_t, const StoredEdge*, AnyObj::C_HEAP, mtTracing> SampleToLeakContextEdgeMap;
+static SampleToLeakContextEdgeMap* _sample_to_leak_context_edge_map = nullptr;
 
 EdgeStore::EdgeStore() : _edges(new EdgeHashTable(this)) {}
 
 EdgeStore::~EdgeStore() {
   assert(_edges != nullptr, "invariant");
   delete _edges;
-  delete _leak_context_edges;
-  _leak_context_edges = nullptr;
+  delete _sample_to_leak_context_edge_map;
+  _sample_to_leak_context_edge_map = nullptr;
 }
 
-static int leak_context_edge_idx(const ObjectSample* sample) {
+static const StoredEdge* leak_context_edge(const ObjectSample* sample) {
   assert(sample != nullptr, "invariant");
-  return static_cast<int>(sample->object()->mark().value()) >> markWord::lock_bits;
+  assert(_sample_to_leak_context_edge_map != nullptr, "invariant");
+  const StoredEdge** edge = _sample_to_leak_context_edge_map->get(p2u(sample->object()));
+  return edge != nullptr ? *edge : nullptr;
 }
 
 bool EdgeStore::has_leak_context(const ObjectSample* sample) const {
-  const int idx = leak_context_edge_idx(sample);
-  if (idx == 0) {
-    return false;
-  }
-  assert(idx > 0, "invariant");
-  assert(_leak_context_edges != nullptr, "invariant");
-  assert(idx < _leak_context_edges->length(), "invariant");
-  assert(_leak_context_edges->at(idx) != nullptr, "invariant");
-  return true;
+  return _sample_to_leak_context_edge_map != nullptr && leak_context_edge(sample) != nullptr;
 }
 
 const StoredEdge* EdgeStore::get(const ObjectSample* sample) const {
   assert(sample != nullptr, "invariant");
-  if (_leak_context_edges != nullptr) {
+  if (_sample_to_leak_context_edge_map != nullptr) {
     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
-    const int idx = leak_context_edge_idx(sample);
-    if (idx > 0) {
-      assert(idx < _leak_context_edges->length(), "invariant");
-      const StoredEdge* const edge =_leak_context_edges->at(idx);
-      assert(edge != nullptr, "invariant");
+    const StoredEdge* const edge = leak_context_edge(sample);
+    if (edge != nullptr) {
       return edge;
     }
   }
   return get(UnifiedOopRef::encode_in_native(sample->object_addr()));
 }
 
-#ifdef ASSERT
-// max_idx to ensure idx fit in lower 32-bits of markword together with lock bits.
-static constexpr const int max_idx =  right_n_bits(32 - markWord::lock_bits);
+static constexpr const unsigned max_map_size = max_jint >> 1;
 
-static void store_idx_precondition(oop sample_object, int idx) {
-  assert(sample_object != nullptr, "invariant");
-  assert(sample_object->mark().is_marked(), "invariant");
-  assert(idx > 0, "invariant");
-  assert(idx <= max_idx, "invariant");
-}
-#endif
-
-static void store_idx_in_markword(oop sample_object, int idx) {
-  DEBUG_ONLY(store_idx_precondition(sample_object, idx);)
-  const markWord idx_mark_word(sample_object->mark().value() | idx << markWord::lock_bits);
-  sample_object->set_mark(idx_mark_word);
-  assert(sample_object->mark().is_marked(), "must still be marked");
-}
-
-static const int initial_size = 64;
-
-static int save(const StoredEdge* edge) {
-  assert(edge != nullptr, "invariant");
-  if (_leak_context_edges == nullptr) {
-    _leak_context_edges = new (mtTracing) GrowableArray<const StoredEdge*>(initial_size, mtTracing);
-    _leak_context_edges->append(nullptr); // next idx now at 1, for disambiguation in markword.
+static inline unsigned map_size() {
+  assert(JfrOptionSet::old_object_queue_size() > 0, "invariant");
+  unsigned size = JfrOptionSet::old_object_queue_size();
+  size = round_up_power_of_2(size);
+  if (size < 1024) {
+    return 1024;
   }
-  return _leak_context_edges->append(edge);
+  size <<= 1;
+  return size >= max_map_size ? max_map_size : size;
 }
 
-// We associate the leak context edge with the leak candidate object by saving the
-// edge in an array and storing the array idx (shifted) into the markword of the candidate object.
 static void associate_with_candidate(const StoredEdge* leak_context_edge) {
   assert(leak_context_edge != nullptr, "invariant");
-  store_idx_in_markword(leak_context_edge->pointee(), save(leak_context_edge));
+  if (_sample_to_leak_context_edge_map == nullptr) {
+    const unsigned size = map_size();
+    _sample_to_leak_context_edge_map = new (mtTracing) SampleToLeakContextEdgeMap(size, size);
+  }
+  assert(_sample_to_leak_context_edge_map != nullptr, "invariant");
+  _sample_to_leak_context_edge_map->put(p2u(leak_context_edge->pointee()), leak_context_edge);
 }
 
 StoredEdge* EdgeStore::associate_leak_context_with_candidate(const Edge* edge) {

src/hotspot/share/jfr/leakprofiler/chains/edgeStore.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,7 +39,6 @@ class StoredEdge : public Edge {
   size_t _skip_length;
 
  public:
-  StoredEdge();
   StoredEdge(const Edge* parent, UnifiedOopRef reference);
   StoredEdge(const Edge& edge);
   StoredEdge(const StoredEdge& edge);