NOT FOR LANDING. Perf test of global handle Reset operation.

test/cctest/test-global-handles.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 451 matching lines @@
     g1.SetWeak();
     g2.Reset(isolate, v8::Object::New(isolate));
     g2.SetWeak();
   }
 
   CHECK_EQ(0, isolate->NumberOfPhantomHandleResetsSinceLastCall());
   CcTest::i_isolate()->heap()->CollectAllAvailableGarbage();
   CHECK_EQ(2, isolate->NumberOfPhantomHandleResetsSinceLastCall());
   CHECK_EQ(0, isolate->NumberOfPhantomHandleResetsSinceLastCall());
 }
+
+const int N = 1000000;
+v8::Global<v8::Object> gs[N];
+
+TEST(HandleResetPerf) {
+  CcTest::InitializeVM();
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope scope(isolate);
+  std::vector<int> permutation;
+  for (int i = 0; i < N; i++) {
+    permutation.push_back(i);
+  }
+  // Comment it out to make clearing in-order.
+  std::random_shuffle(permutation.begin(), permutation.end());
+  v8::Local<v8::Object> o = v8::Object::New(isolate);
+  double t1 = CcTest::i_isolate()->heap()->MonotonicallyIncreasingTimeInMs();
+  for (int i = 0; i < N; i++) {
+    gs[i].Reset(isolate, o);
+  }
+  double t2 = CcTest::i_isolate()->heap()->MonotonicallyIncreasingTimeInMs();
+  int sum = 0;
+  for (int i = 0; i < N; i++) {
+    sum += permutation[i];
+    gs[permutation[i]].Reset();
+  }
+  double t3 = CcTest::i_isolate()->heap()->MonotonicallyIncreasingTimeInMs();
+  for (int i = 0; i < N; i++) {
+    gs[i].Reset(isolate, o);
+  }
+  double t4 = CcTest::i_isolate()->heap()->MonotonicallyIncreasingTimeInMs();
+  for (int i = 0; i < N; i++) {
+    sum += permutation[i];
+    gs[i].Reset();
+  }
+  double t5 = CcTest::i_isolate()->heap()->MonotonicallyIncreasingTimeInMs();
+  printf("allocation1 %.3f\n", t2 - t1);
+  printf("clear1 %.3f\n", t3 - t2);
+  printf("alloaction2 %.3f\n", t4 - t3);
+  printf("clear2 %.3f\n", t5 - t4);
+  printf("sum %d\n", sum);
+}