diff --git a/src/command_line.cc b/src/command_line.cc
index 40d37708..beb72729 100644
--- a/src/command_line.cc
+++ b/src/command_line.cc
@@ -35,7 +35,7 @@ namespace {
 
 const int kNumIndexers = 8 - 1;
 const int kMaxWorkspaceSearchResults = 1000;
-const bool kUseMultipleProcesses = true;
+const bool kUseMultipleProcesses = false;
 
 
 
@@ -87,43 +87,71 @@ struct IpcManager {
   static constexpr const char* kIpcLanguageClientName = "language_client";
   static constexpr const int kQueueSizeBytes = 1024 * 8;
 
-  std::unique_ptr<ThreadedQueue<std::unique_ptr<BaseIpcMessage>>> threaded_queue_;
-  std::unique_ptr<IpcMessageQueue> ipc_queue_;
-
-  IpcManager() {
-    ipc_queue_ = BuildIpcMessageQueue(kIpcLanguageClientName, kQueueSizeBytes);
+  static IpcManager* instance_;
+  static IpcManager* instance() {
+    if (!instance_)
+      instance_ = new IpcManager();
+    return instance_;
   }
 
+  std::unique_ptr<ThreadedQueue<std::unique_ptr<BaseIpcMessage>>> threaded_queue_for_client_;
+  std::unique_ptr<ThreadedQueue<std::unique_ptr<BaseIpcMessage>>> threaded_queue_for_server_;
+  std::unique_ptr<IpcMessageQueue> ipc_queue_;
 
+  enum class Destination {
+    Client, Server
+  };
+
+  MessageQueue* GetMessageQueue(Destination destination) {
+    assert(kUseMultipleProcesses);
+    return destination == Destination::Client ? &ipc_queue_->for_client : &ipc_queue_->for_server;
+  }
+  ThreadedQueue<std::unique_ptr<BaseIpcMessage>>* GetThreadedQueue(Destination destination) {
+    assert(!kUseMultipleProcesses);
+    return destination == Destination::Client ? threaded_queue_for_client_.get() : threaded_queue_for_server_.get();
+  }
 
   void SendOutMessageToClient(lsBaseOutMessage& response) {
     std::ostringstream sstream;
     response.Write(sstream);
 
-    Ipc_Cout out;
-    out.content = sstream.str();
-    ipc_queue_->SendMessage(&ipc_queue_->for_client, Ipc_Cout::kIpcId, out);
+    if (kUseMultipleProcesses) {
+      Ipc_Cout out;
+      out.content = sstream.str();
+      ipc_queue_->SendMessage(&ipc_queue_->for_client, Ipc_Cout::kIpcId, out);
+    }
+    else {
+      auto out = MakeUnique<Ipc_Cout>();
+      out->content = sstream.str();
+      GetThreadedQueue(Destination::Client)->Enqueue(std::move(out));
+    }
   }
 
-  enum class Destination {
-    Client, Server
-  };
-  void SendMessageWithId(Destination destination, IpcId id, BaseIpcMessage& message) {
-    ipc_queue_->SendMessage(
-      destination == Destination::Client ? &ipc_queue_->for_client : &ipc_queue_->for_server,
-      id,
-      message);
-  }
-  template <typename TMessage>
-  void SendMessage(Destination destination, TMessage& message) {
-    SendMessageWithId(destination, TMessage::kIpcId, message);
+  void SendMessage(Destination destination, std::unique_ptr<BaseIpcMessage> message) {
+    if (kUseMultipleProcesses)
+      ipc_queue_->SendMessage(GetMessageQueue(destination), message->method_id, *message);
+    else
+      GetThreadedQueue(destination)->Enqueue(std::move(message));
   }
 
   std::vector<std::unique_ptr<BaseIpcMessage>> GetMessages(Destination destination) {
-    return ipc_queue_->GetMessages(destination == Destination::Client ? &ipc_queue_->for_client : &ipc_queue_->for_server);
+    if (kUseMultipleProcesses)
+      return ipc_queue_->GetMessages(GetMessageQueue(destination));
+    else
+      return GetThreadedQueue(destination)->DequeueAll();
   }
 
  private:
+  IpcManager() {
+    if (kUseMultipleProcesses) {
+      ipc_queue_ = BuildIpcMessageQueue(kIpcLanguageClientName, kQueueSizeBytes);
+    }
+    else {
+      threaded_queue_for_client_ = MakeUnique<ThreadedQueue<std::unique_ptr<BaseIpcMessage>>>();
+      threaded_queue_for_server_ = MakeUnique<ThreadedQueue<std::unique_ptr<BaseIpcMessage>>>();
+    }
+  }
+
   template<typename T>
   void RegisterId(IpcMessageQueue* t) {
     t->RegisterId(T::kIpcId,
@@ -164,7 +192,7 @@ struct IpcManager {
   }
 };
 
-
+IpcManager* IpcManager::instance_ = nullptr;
 
 
 
@@ -987,7 +1015,6 @@ void IndexMain(
 
 void QueryDbMainLoop(
   QueryDatabase* db,
-  IpcManager* language_client,
   Index_DoIndexQueue* queue_do_index,
   Index_DoIdMapQueue* queue_do_id_map,
   Index_OnIdMappedQueue* queue_on_id_mapped,
@@ -995,10 +1022,11 @@ void QueryDbMainLoop(
   Project* project,
   WorkingFiles* working_files,
   CompletionManager* completion_manager) {
+  IpcManager* ipc = IpcManager::instance();
 
-  std::vector<std::unique_ptr<BaseIpcMessage>> messages = language_client->GetMessages(IpcManager::Destination::Server);
+  std::vector<std::unique_ptr<BaseIpcMessage>> messages = ipc->GetMessages(IpcManager::Destination::Server);
   for (auto& message : messages) {
-    //std::cerr << "[querydb] Processing message " << static_cast<int>(message->method_id) << std::endl;
+    std::cerr << "[querydb] Processing message " << IpcIdToString(message->method_id) << std::endl;
 
     switch (message->method_id) {
     case IpcId::Quit: {
@@ -1008,8 +1036,8 @@ void QueryDbMainLoop(
     }
 
     case IpcId::IsAlive: {
-      Ipc_IsAlive response;
-      language_client->SendMessageWithId(IpcManager::Destination::Client, response.method_id, response);
+      std::cerr << "[querydb] Sending IsAlive response to client" << std::endl;
+      ipc->SendMessage(IpcManager::Destination::Client, MakeUnique<Ipc_IsAlive>());
       break;
     }
 
@@ -1051,7 +1079,7 @@ void QueryDbMainLoop(
     }
     case IpcId::TextDocumentDidClose: {
       auto msg = static_cast<Ipc_TextDocumentDidClose*>(message.get());
-      std::cerr << "Closing " << msg->params.textDocument.uri.GetPath() << std::endl;
+      //std::cerr << "Closing " << msg->params.textDocument.uri.GetPath() << std::endl;
       working_files->OnClose(msg->params);
       break;
     }
@@ -1096,7 +1124,7 @@ void QueryDbMainLoop(
       }
 
       response.Write(std::cerr);
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1174,7 +1202,7 @@ void QueryDbMainLoop(
           break;
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1210,7 +1238,7 @@ void QueryDbMainLoop(
         break;
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1236,7 +1264,7 @@ void QueryDbMainLoop(
         break;
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1273,7 +1301,7 @@ void QueryDbMainLoop(
         break;
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1299,7 +1327,7 @@ void QueryDbMainLoop(
         response.result.push_back(info);
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1393,7 +1421,7 @@ void QueryDbMainLoop(
         };
       }
 
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
@@ -1433,13 +1461,12 @@ void QueryDbMainLoop(
       }
 
       std::cerr << "- Found " << response.result.size() << " results for query " << query << std::endl;
-      language_client->SendOutMessageToClient(response);
+      ipc->SendOutMessageToClient(response);
       break;
     }
 
     default: {
-      std::cerr << "1 Unhandled IPC message with kind "
-        << static_cast<int>(message->method_id) << std::endl;
+      std::cerr << "[querydb] Unhandled IPC message " << IpcIdToString(message->method_id) << std::endl;
       exit(1);
     }
     }
@@ -1485,7 +1512,6 @@ void QueryDbMain() {
   //std::cerr << "Running QueryDb" << std::endl;
 
   // Create queues.
-  IpcManager ipc;
   Index_DoIndexQueue queue_do_index;
   Index_DoIdMapQueue queue_do_id_map;
   Index_OnIdMappedQueue queue_on_id_mapped;
@@ -1506,7 +1532,7 @@ void QueryDbMain() {
   // Run query db main loop.
   QueryDatabase db;
   while (true) {
-    QueryDbMainLoop(&db, &ipc, &queue_do_index, &queue_do_id_map, &queue_on_id_mapped, &queue_on_indexed, &project, &working_files, &completion_manager);
+    QueryDbMainLoop(&db, &queue_do_index, &queue_do_id_map, &queue_on_id_mapped, &queue_on_indexed, &project, &working_files, &completion_manager);
     std::this_thread::sleep_for(std::chrono::milliseconds(10));
   }
 }
@@ -1581,7 +1607,9 @@ void QueryDbMain() {
 // blocks.
 //
 // |ipc| is connected to a server.
-void LanguageServerStdinLoop(IpcManager* ipc) {
+void LanguageServerStdinLoop() {
+  IpcManager* ipc = IpcManager::instance();
+
   while (true) {
     std::unique_ptr<BaseIpcMessage> message = MessageRegistry::instance()->ReadMessageFromStdin();
 
@@ -1589,8 +1617,7 @@ void LanguageServerStdinLoop(IpcManager* ipc) {
     if (!message)
       continue;
 
-    //std::cerr << "[info]: Got message of type "
-    //  << IpcIdToString(message->method_id) << std::endl;
+    std::cerr << "[stdin]: Got message \"" << IpcIdToString(message->method_id) << '"' << std::endl;
     switch (message->method_id) {
       // TODO: For simplicitly lets just proxy the initialize request like
       // all other requests so that stdin loop thread becomes super simple.
@@ -1601,9 +1628,9 @@ void LanguageServerStdinLoop(IpcManager* ipc) {
         std::cerr << "Initialize in directory " << project_path
           << " with uri " << request->params.rootUri->raw_uri
           << std::endl;
-        Ipc_OpenProject open_project;
-        open_project.project_path = project_path;
-        ipc->SendMessageWithId(IpcManager::Destination::Server, Ipc_OpenProject::kIpcId, open_project);
+        auto open_project = MakeUnique<Ipc_OpenProject>();
+        open_project->project_path = project_path;
+        ipc->SendMessage(IpcManager::Destination::Server, std::move(open_project));
       }
 
       // TODO: query request->params.capabilities.textDocument and support only things
@@ -1664,42 +1691,43 @@ void LanguageServerStdinLoop(IpcManager* ipc) {
     case IpcId::TextDocumentDocumentSymbol:
     case IpcId::TextDocumentCodeLens:
     case IpcId::WorkspaceSymbol: {
-      //std::cerr << "Sending message " << (int)message->method_id << std::endl;
-      ipc->SendMessageWithId(IpcManager::Destination::Server, message->method_id, *message.get());
+      ipc->SendMessage(IpcManager::Destination::Server, std::move(message));
       break;
     }
 
     default: {
-      std::cerr << "3 Unhandled IPC message with kind "
-        << static_cast<int>(message->method_id) << std::endl;
+      std::cerr << "[stdin] Unhandled IPC message " << IpcIdToString(message->method_id) << std::endl;
       exit(1);
     }
     }
   }
 }
 
-void LanguageServerMainLoop(IpcManager* ipc) {
+void LanguageServerMainLoop() {
+  IpcManager* ipc = IpcManager::instance();
+
   std::vector<std::unique_ptr<BaseIpcMessage>> messages = ipc->GetMessages(IpcManager::Destination::Client);
   for (auto& message : messages) {
+    std::cerr << "[server] Processing message " << IpcIdToString(message->method_id) << std::endl;
+
     switch (message->method_id) {
-    case IpcId::Quit: {
-      std::cerr << "Got quit message (exiting)" << std::endl;
-      exit(0);
-      break;
-    }
+      case IpcId::Quit: {
+        std::cerr << "[server] Got quit message (exiting)" << std::endl;
+        exit(0);
+        break;
+      }
 
-    case IpcId::Cout: {
-      auto msg = static_cast<Ipc_Cout*>(message.get());
-      std::cout << msg->content;
-      std::cout.flush();
-      break;
-    }
+      case IpcId::Cout: {
+        auto msg = static_cast<Ipc_Cout*>(message.get());
+        std::cout << msg->content;
+        std::cout.flush();
+        break;
+      }
 
-    default: {
-      std::cerr << "2 Unhandled IPC message with kind "
-        << static_cast<int>(message->method_id) << std::endl;
-      exit(1);
-    }
+      default: {
+        std::cerr << "[server] Unhandled IPC message " << IpcIdToString(message->method_id) << std::endl;
+        exit(1);
+      }
     }
   }
 }
@@ -1751,10 +1779,19 @@ void LanguageServerMainLoop(IpcManager* ipc) {
 
 
 
-bool IsQueryDbProcessRunning(IpcManager* ipc) {
+bool IsQueryDbProcessRunning() {
+  if (!kUseMultipleProcesses)
+    return false;
+
+  IpcManager* ipc = IpcManager::instance();
+
+  // Discard any left-over messages from previous runs.
+  if (kUseMultipleProcesses)
+    ipc->GetMessages(IpcManager::Destination::Client);
+
   // Emit an alive check. Sleep so the server has time to respond.
-  Ipc_IsAlive check_alive;
-  ipc->SendMessage(IpcManager::Destination::Server, check_alive);
+  std::cerr << "[setup] Sending IsAlive request to server" << std::endl;
+  ipc->SendMessage(IpcManager::Destination::Server, MakeUnique<Ipc_IsAlive>());
 
   // TODO: Tune this value or make it configurable.
   std::this_thread::sleep_for(std::chrono::milliseconds(100));
@@ -1766,16 +1803,14 @@ bool IsQueryDbProcessRunning(IpcManager* ipc) {
       return true;
   }
 
+  // No response back. Clear out server messages so server doesn't respond to stale request.
+  ipc->GetMessages(IpcManager::Destination::Server);
+
   return false;
 }
 
-void LanguageServerMain(std::string process_name) {
-  IpcManager ipc;
-
-  // Discard any left-over messages from previous runs.
-  ipc.GetMessages(IpcManager::Destination::Client);
-
-  bool has_server = IsQueryDbProcessRunning(&ipc);
+void LanguageServerMain() {
+  bool has_server = IsQueryDbProcessRunning();
 
   // No server is running. Start it in-process. If the user wants to run the
   // server out of process they have to start it themselves.
@@ -1784,9 +1819,9 @@ void LanguageServerMain(std::string process_name) {
   }
 
   // Run language client.
-  new std::thread(&LanguageServerStdinLoop, &ipc);
+  new std::thread(&LanguageServerStdinLoop);
   while (true) {
-    LanguageServerMainLoop(&ipc);
+    LanguageServerMainLoop();
     std::this_thread::sleep_for(std::chrono::milliseconds(10));
   }
 }
@@ -1900,7 +1935,7 @@ int main(int argc, char** argv) {
   }
   else if (HasOption(options, "--language-server")) {
     //std::cerr << "Running language server" << std::endl;
-    LanguageServerMain(argv[0]);
+    LanguageServerMain();
     return 0;
   }
   else if (HasOption(options, "--querydb")) {
@@ -1910,7 +1945,7 @@ int main(int argc, char** argv) {
   }
   else {
     //std::cerr << "Running language server" << std::endl;
-    LanguageServerMain(argv[0]);
+    LanguageServerMain();
     return 0;
   }
 
diff --git a/src/ipc.cc b/src/ipc.cc
index d4007193..5d455490 100644
--- a/src/ipc.cc
+++ b/src/ipc.cc
@@ -38,8 +38,18 @@ const char* IpcIdToString(IpcId id) {
     return "codeLens/resolve";
   case IpcId::WorkspaceSymbol:
     return "workspace/symbol";
+
+
+  case IpcId::Quit:
+    return "$quit";
+  case IpcId::IsAlive:
+    return "$isAlive";
+  case IpcId::OpenProject:
+    return "$openProject";
+  case IpcId::Cout:
+    return "$cout";
   default:
-    assert(false);
+    assert(false && "missing IpcId string name");
     exit(1);
   }
 }
diff --git a/src/platform_win.cc b/src/platform_win.cc
index 9d5a28e4..be6ceea7 100644
--- a/src/platform_win.cc
+++ b/src/platform_win.cc
@@ -41,7 +41,7 @@ struct PlatformMutexWin : public PlatformMutex {
   HANDLE raw_mutex = INVALID_HANDLE_VALUE;
 
   PlatformMutexWin(const std::string& name) {
-    //std::cerr << "[win] Creating mutex with name " << name << std::endl;
+    std::cerr << "[win] Creating mutex with name " << name << std::endl;
     raw_mutex = CreateMutex(nullptr, false /*initial_owner*/, name.c_str());
     CheckForError({ ERROR_ALREADY_EXISTS });
   }
@@ -72,8 +72,8 @@ struct PlatformSharedMemoryWin : public PlatformSharedMemory {
   HANDLE shmem_;
 
   PlatformSharedMemoryWin(const std::string& name, size_t capacity) {
-    //std::cerr << "[win] Creating shared memory with name " << name
-    //  << " and capacity " << capacity << std::endl;
+    std::cerr << "[win] Creating shared memory with name " << name
+      << " and capacity " << capacity << std::endl;
     this->name = name;
 
     shmem_ = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
diff --git a/src/threaded_queue.h b/src/threaded_queue.h
index c8f412fd..ca0985ea 100644
--- a/src/threaded_queue.h
+++ b/src/threaded_queue.h
@@ -21,6 +21,19 @@ public:
     cv_.notify_one();
   }
 
+  // Return all elements in the queue.
+  std::vector<T> DequeueAll() {
+    std::lock_guard<std::mutex> lock(mutex_);
+
+    std::vector<T> result;
+    result.reserve(queue_.size());
+    while (!queue_.empty()) {
+      result.emplace_back(std::move(queue_.front()));
+      queue_.pop();
+    }
+    return result;
+  }
+
   // Get the "front"-element.
   // If the queue is empty, wait untill an element is avaiable.
   T Dequeue() {
@@ -38,7 +51,7 @@ public:
   // Get the first element from the queue without blocking. Returns a null
   // value if the queue is empty.
   optional<T> TryDequeue() {
-    std::unique_lock<std::mutex> lock(mutex_);
+    std::lock_guard<std::mutex> lock(mutex_);
     if (queue_.empty())
       return nullopt;