Revert VM thread cleanup

runtime/vm/dart.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/dart.h"
 
 #include "vm/code_observers.h"
 #include "vm/cpu.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/flags.h"
 #include "vm/freelist.h"
 #include "vm/handles.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
-#include "vm/message.h"
 #include "vm/metrics.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/object_id_ring.h"
 #include "vm/port.h"
 #include "vm/profiler.h"
 #include "vm/service_isolate.h"
 #include "vm/simulator.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
@@ skipping 150 matching lines @@
   Isolate::SetUnhandledExceptionCallback(unhandled);
   Isolate::SetShutdownCallback(shutdown);
 
   ServiceIsolate::Run();
 
   return NULL;
 }
 
 
 const char* Dart::Cleanup() {
-  ASSERT(Isolate::Current() == NULL);
+  // Shutdown the service isolate before shutting down the thread pool.
+  ServiceIsolate::Shutdown();
+#if 0
+  // Ideally we should shutdown the VM isolate here, but the thread pool
+  // shutdown does not seem to ensure that all the threads have stopped
+  // execution before it terminates, this results in racing isolates.
   if (vm_isolate_ == NULL) {
     return "VM already terminated.";
   }
 
-  // Disable the creation of new isolates.
-  Isolate::DisableIsolateCreation();
+  ASSERT(Isolate::Current() == NULL);
 
-  // Send the OOB Kill message to all remaining isolates.
-  Isolate::KillAllIsolates();
-
-  // Shutdown the service isolate before shutting down the thread pool.
-  ServiceIsolate::Shutdown();
-
-  // Shutdown the thread pool. On return, all thread pool threads have exited.
   delete thread_pool_;
   thread_pool_ = NULL;
 
   // Set the VM isolate as current isolate.
   Thread::EnsureInit();
   Thread::EnterIsolate(vm_isolate_);
 
+  // There is a planned and known asymmetry here: We exit one scope for the VM
+  // isolate to account for the scope that was entered in Dart_InitOnce.
+  Dart_ExitScope();
+
   ShutdownIsolate();
   vm_isolate_ = NULL;
 
   TargetCPUFeatures::Cleanup();
+#endif
+
   Profiler::Shutdown();
   CodeObservers::DeleteAll();
 
-  ASSERT(Isolate::IsolateCount() == 0);
   return NULL;
 }
 
 
 Isolate* Dart::CreateIsolate(const char* name_prefix,
                              const Dart_IsolateFlags& api_flags) {
   // Create a new isolate.
   Isolate* isolate = Isolate::Init(name_prefix, api_flags);
+  ASSERT(isolate != NULL);
   return isolate;
 }
 
 
 RawError* Dart::InitializeIsolate(const uint8_t* snapshot_buffer, void* data) {
   // Initialize the new isolate.
   Isolate* isolate = Isolate::Current();
   TIMERSCOPE(isolate, time_isolate_initialization);
   ASSERT(isolate != NULL);
   StackZone zone(isolate);
@@ skipping 117 matching lines @@
   return predefined_handles_->handles_.IsValidScopedHandle(address);
 }
 
 
 bool Dart::IsReadOnlyApiHandle(Dart_Handle handle) {
   ASSERT(predefined_handles_ != NULL);
   return predefined_handles_->api_handles_.IsValidHandle(handle);
 }
 
 }  // namespace dart