Fix thread-interrupter shutdown on Windows.

runtime/vm/thread_interrupter.cc

 // Copyright (c) 2013, 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 "vm/simulator.h"
 #include "vm/thread_interrupter.h"
 
 namespace dart {
 
 // Notes:
@@ skipping 68 matching lines @@
     }
   }
   ASSERT(interrupter_thread_id_ != Thread::kInvalidThreadId);
   if (FLAG_trace_thread_interrupter) {
     OS::Print("ThreadInterrupter running.\n");
   }
 }
 
 
 void ThreadInterrupter::Shutdown() {
-  if (shutdown_) {
-    // Already shutdown.
-    return;
-  }
-  ASSERT(initialized_);
-  if (FLAG_trace_thread_interrupter) {
-    OS::Print("ThreadInterrupter shutting down.\n");
-  }
-  {
-    MonitorLocker ml(monitor_);
-    shutdown_ = true;
-  }
   {
     MonitorLocker shutdown_ml(monitor_);
+    if (shutdown_) {
+      // Already shutdown.
+      return;
+    }
+    shutdown_ = true;
+    ASSERT(initialized_);
+    if (FLAG_trace_thread_interrupter) {
+      OS::Print("ThreadInterrupter shutting down.\n");
+    }
     while (thread_running_) {
       shutdown_ml.Wait();
     }
+    // Join in the interrupter thread. On Windows, a thread's exit-code can
+    // leak into the process's exit-code, if exiting 'at same time' as the
+    // process ends.
+    if (interrupter_thread_id_ != Thread::kInvalidThreadId) {
+      Thread::Join(interrupter_thread_id_);
+      interrupter_thread_id_ = Thread::kInvalidThreadId;
+    }
   }
-  interrupter_thread_id_ = Thread::kInvalidThreadId;
   if (FLAG_trace_thread_interrupter) {
     OS::Print("ThreadInterrupter shut down.\n");
   }
 }
 
 // Delay between interrupts.
 void ThreadInterrupter::SetInterruptPeriod(intptr_t period) {
   if (shutdown_) {
     return;
   }
@@ skipping 109 matching lines @@
 
 void ThreadInterrupter::ThreadMain(uword parameters) {
   ASSERT(initialized_);
   InstallSignalHandler();
   if (FLAG_trace_thread_interrupter) {
     OS::Print("ThreadInterrupter thread running.\n");
   }
   {
     // Signal to main thread we are ready.
     MonitorLocker startup_ml(monitor_);
+    interrupter_thread_id_ = Thread::GetCurrentThreadId();
     thread_running_ = true;
-    interrupter_thread_id_ = Thread::GetCurrentThreadId();
     startup_ml.Notify();
   }
   {
     MonitorLocker wait_ml(monitor_);
     ThreadInterrupterVisitIsolates visitor;
     while (!shutdown_) {
       Isolate::VisitIsolates(&visitor);
       wait_ml.WaitMicros(interrupt_period_);
     }
   }
   if (FLAG_trace_thread_interrupter) {
     OS::Print("ThreadInterrupter thread exiting.\n");
   }
   {
     // Signal to main thread we are exiting.
     MonitorLocker shutdown_ml(monitor_);
     thread_running_ = false;
     shutdown_ml.Notify();
   }
 }
 
 }  // namespace dart