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

test/cctest/test-global-handles.cc

Index: test/cctest/test-global-handles.cc
diff --git a/test/cctest/test-global-handles.cc b/test/cctest/test-global-handles.cc
index 06e7466dc68fa7727d9379fae24cfd60b135b570..6c2d2d089aacee7a14bc4cefbd2c8fd5d388bbb7 100644
--- a/test/cctest/test-global-handles.cc
+++ b/test/cctest/test-global-handles.cc
@@ -469,3 +469,44 @@ TEST(PhatomHandlesWithoutCallbacks) {
   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);
+}