- Do not repeatedly allocate and release Monitor objects.

runtime/vm/thread_barrier_test.cc

Index: runtime/vm/thread_barrier_test.cc
diff --git a/runtime/vm/thread_barrier_test.cc b/runtime/vm/thread_barrier_test.cc
index 4517e18d95766079341f680224e62207bd4b1d14..7ca11c64690a7e8f024011f14f5050bb854efa84 100644
--- a/runtime/vm/thread_barrier_test.cc
+++ b/runtime/vm/thread_barrier_test.cc
@@ -46,14 +46,21 @@ UNIT_TEST_CASE(ThreadBarrier) {
   static const intptr_t kNumTasks = 5;
   static const intptr_t kNumRounds = 500;
 
-  ThreadBarrier barrier(kNumTasks + 1);
-  for (intptr_t i = 0; i < kNumTasks; ++i) {
-    Dart::thread_pool()->Run(new FuzzTask(kNumRounds, &barrier, i + 1));
-  }
-  for (intptr_t i = 0; i < kNumRounds; ++i) {
-    barrier.Sync();
+  Monitor* monitor = new Monitor();
+  Monitor* monitor_done = new Monitor();
+  {
+    ThreadBarrier barrier(kNumTasks + 1, monitor, monitor_done);
+    for (intptr_t i = 0; i < kNumTasks; ++i) {
+      Dart::thread_pool()->Run(new FuzzTask(kNumRounds, &barrier, i + 1));
+    }
+    for (intptr_t i = 0; i < kNumRounds; ++i) {
+      barrier.Sync();
+    }
+    barrier.Exit();
   }
-  barrier.Exit();
+
+  delete monitor_done;
+  delete monitor;
 }
 
 }  // namespace dart