Revert of [heap] Uncommit pooled pages concurrently

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 139 matching lines @@
       old_generation_size_at_last_gc_(0),
       gcs_since_last_deopt_(0),
       global_pretenuring_feedback_(nullptr),
       ring_buffer_full_(false),
       ring_buffer_end_(0),
       promotion_queue_(this),
       configured_(false),
       current_gc_flags_(Heap::kNoGCFlags),
       current_gc_callback_flags_(GCCallbackFlags::kNoGCCallbackFlags),
       external_string_table_(this),
+      chunks_queued_for_free_(NULL),
+      concurrent_unmapping_tasks_active_(0),
+      pending_unmapping_tasks_semaphore_(0),
       gc_callbacks_depth_(0),
       deserialization_complete_(false),
       strong_roots_list_(NULL),
       array_buffer_tracker_(NULL),
       heap_iterator_depth_(0),
       force_oom_(false) {
 // Allow build-time customization of the max semispace size. Building
 // V8 with snapshots and a non-default max semispace size is much
 // easier if you can define it as part of the build environment.
 #if defined(V8_MAX_SEMISPACE_SIZE)
@@ skipping 5265 matching lines @@
     delete memory_reducer_;
     memory_reducer_ = nullptr;
   }
 
   delete object_stats_;
   object_stats_ = nullptr;
 
   delete scavenge_job_;
   scavenge_job_ = nullptr;
 
+  WaitUntilUnmappingOfFreeChunksCompleted();
+
   delete array_buffer_tracker_;
   array_buffer_tracker_ = nullptr;
 
   isolate_->global_handles()->TearDown();
 
   external_string_table_.TearDown();
 
   delete tracer_;
   tracer_ = nullptr;
 
@@ skipping 785 matching lines @@
     heap_->FinalizeExternalString(ExternalString::cast(new_space_strings_[i]));
   }
   new_space_strings_.Free();
   for (int i = 0; i < old_space_strings_.length(); ++i) {
     heap_->FinalizeExternalString(ExternalString::cast(old_space_strings_[i]));
   }
   old_space_strings_.Free();
 }
 
 
+class Heap::UnmapFreeMemoryTask : public v8::Task {
+ public:
+  UnmapFreeMemoryTask(Heap* heap, MemoryChunk* head)
+      : heap_(heap), head_(head) {}
+  virtual ~UnmapFreeMemoryTask() {}
+
+ private:
+  // v8::Task overrides.
+  void Run() override {
+    heap_->FreeQueuedChunks(head_);
+    heap_->pending_unmapping_tasks_semaphore_.Signal();
+  }
+
+  Heap* heap_;
+  MemoryChunk* head_;
+
+  DISALLOW_COPY_AND_ASSIGN(UnmapFreeMemoryTask);
+};
+
+
+void Heap::WaitUntilUnmappingOfFreeChunksCompleted() {
+  while (concurrent_unmapping_tasks_active_ > 0) {
+    pending_unmapping_tasks_semaphore_.Wait();
+    concurrent_unmapping_tasks_active_--;
+  }
+}
+
+
+void Heap::QueueMemoryChunkForFree(MemoryChunk* chunk) {
+  // PreFree logically frees the memory chunk. However, the actual freeing
+  // will happen on a separate thread sometime later.
+  memory_allocator()->PreFreeMemory(chunk);
+
+  // The chunks added to this queue will be freed by a concurrent thread.
+  chunk->set_next_chunk(chunks_queued_for_free_);
+  chunks_queued_for_free_ = chunk;
+}
+
+
+void Heap::FreeQueuedChunks() {
+  if (chunks_queued_for_free_ != NULL) {
+    if (FLAG_concurrent_sweeping) {
+      V8::GetCurrentPlatform()->CallOnBackgroundThread(
+          new UnmapFreeMemoryTask(this, chunks_queued_for_free_),
+          v8::Platform::kShortRunningTask);
+    } else {
+      FreeQueuedChunks(chunks_queued_for_free_);
+      pending_unmapping_tasks_semaphore_.Signal();
+    }
+    chunks_queued_for_free_ = NULL;
+  } else {
+    // If we do not have anything to unmap, we just signal the semaphore
+    // that we are done.
+    pending_unmapping_tasks_semaphore_.Signal();
+  }
+  concurrent_unmapping_tasks_active_++;
+}
+
+
+void Heap::FreeQueuedChunks(MemoryChunk* list_head) {
+  MemoryChunk* next;
+  MemoryChunk* chunk;
+  for (chunk = list_head; chunk != NULL; chunk = next) {
+    next = chunk->next_chunk();
+    memory_allocator()->PerformFreeMemory(chunk);
+  }
+}
+
+
 void Heap::RememberUnmappedPage(Address page, bool compacted) {
   uintptr_t p = reinterpret_cast<uintptr_t>(page);
   // Tag the page pointer to make it findable in the dump file.
   if (compacted) {
     p ^= 0xc1ead & (Page::kPageSize - 1);  // Cleared.
   } else {
     p ^= 0x1d1ed & (Page::kPageSize - 1);  // I died.
   }
   remembered_unmapped_pages_[remembered_unmapped_pages_index_] =
       reinterpret_cast<Address>(p);
@@ skipping 87 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8