- Do not repeatedly allocate and release Monitor objects.

runtime/vm/thread_barrier_test.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/random.h"
 #include "vm/thread_barrier.h"
 #include "vm/thread_pool.h"
 #include "vm/unit_test.h"
 
@@ skipping 28 matching lines @@
   const intptr_t num_rounds_;
   ThreadBarrier* barrier_;
   Random rng_;
 };
 
 
 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));
+  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();
   }
-  for (intptr_t i = 0; i < kNumRounds; ++i) {
-    barrier.Sync();
-  }
-  barrier.Exit();
+
+  delete monitor_done;
+  delete monitor;
 }
 
 }  // namespace dart