test fix for concurrent chunk pool pruning

Author: roberttoyonaga

src/hotspot/share/memory/arena.cpp

@@ -87,6 +87,7 @@ class ChunkPool {
   // Our four static pools
   static constexpr int _num_pools = 4;
   static ChunkPool _pools[_num_pools];
+  volatile static bool _suspend_cleaning;
 
   Chunk*       _first;
   const size_t _size;         // (inner payload) size of the chunks this pool serves
@@ -135,6 +136,7 @@ class ChunkPool {
   ChunkPool(size_t size) : _first(nullptr), _size(size) {}
 
   static void clean() {
+    if (_suspend_cleaning) return;
     NativeHeapTrimmer::SuspendMark sm("chunk pool cleaner");
     for (int i = 0; i < _num_pools; i++) {
       _pools[i].prune();
@@ -144,6 +146,9 @@ class ChunkPool {
   // Returns an initialized and null-terminated Chunk of requested size
   static Chunk* allocate_chunk(Arena* arena, size_t length, AllocFailType alloc_failmode);
   static void deallocate_chunk(Chunk* p);
+  static void set_suspend_cleaning(bool suspend) {
+    _suspend_cleaning = suspend;
+  }
 };
 
 static bool on_compiler_thread() {
@@ -230,6 +235,7 @@ void ChunkPool::deallocate_chunk(Chunk* c) {
 }
 
 ChunkPool ChunkPool::_pools[] = { Chunk::size, Chunk::medium_size, Chunk::init_size, Chunk::tiny_size };
+volatile bool ChunkPool::_suspend_cleaning = false;
 
 class ChunkPoolCleaner : public PeriodicTask {
   static const int cleaning_interval = 5000; // cleaning interval in ms
@@ -241,6 +247,10 @@ class ChunkPoolCleaner : public PeriodicTask {
    }
 };
 
+void Arena::suspend_chunk_pool_cleaning(bool suspend) {
+  ChunkPool::set_suspend_cleaning(suspend);
+}
+
 void Arena::start_chunk_pool_cleaner_task() {
 #ifdef ASSERT
   static bool task_created = false;

src/hotspot/share/memory/arena.hpp

@@ -159,6 +159,7 @@ class Arena : public CHeapObjBase {
 
  public:
   static void initialize_chunk_pool();
+  static void suspend_chunk_pool_cleaning(bool suspend);
 
   // Start the chunk_pool cleaner task
   static void start_chunk_pool_cleaner_task();

test/hotspot/gtest/nmt/test_nmt_chunk_accounting.cpp

@@ -100,6 +100,7 @@ TEST_VM(NMTChunkAccounting, standard_chunks) {
   static const size_t GROW_SIZE = Chunk::size;
   static const size_t NUM_ALLOCS = 64;
   CountersSnapshot after_grow;
+  Arena::suspend_chunk_pool_cleaning(true);
   {
     Arena arena(mtTest);
     const CountersSnapshot baseline = take_snapshot();