diff --git a/grpc.gemspec b/grpc.gemspec
index c08e333cb30..e8ddd5ae359 100755
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -29,6 +29,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'google-protobuf', '~> 3.0'
   s.add_dependency 'googleauth',      '~> 0.5.1'
+  s.add_dependency 'concurrent-ruby'
 
   s.add_development_dependency 'bundler',            '~> 1.9'
   s.add_development_dependency 'facter',             '~> 2.4'
diff --git a/include/grpc++/ext/reflection.grpc.pb.h b/include/grpc++/ext/reflection.grpc.pb.h
index 0b4ef861472..064117e3030 100644
--- a/include/grpc++/ext/reflection.grpc.pb.h
+++ b/include/grpc++/ext/reflection.grpc.pb.h
@@ -74,6 +74,7 @@
 
 #include <grpc++/impl/codegen/async_stream.h>
 #include <grpc++/impl/codegen/async_unary_call.h>
+#include <grpc++/impl/codegen/method_handler_impl.h>
 #include <grpc++/impl/codegen/proto_utils.h>
 #include <grpc++/impl/codegen/rpc_method.h>
 #include <grpc++/impl/codegen/service_type.h>
@@ -174,6 +175,7 @@ class ServerReflection GRPC_FINAL {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
   };
+  typedef Service StreamedUnaryService;
 };
 
 }  // namespace v1alpha
diff --git a/include/grpc++/impl/codegen/call.h b/include/grpc++/impl/codegen/call.h
index dfac177970a..df225d362b4 100644
--- a/include/grpc++/impl/codegen/call.h
+++ b/include/grpc++/impl/codegen/call.h
@@ -662,10 +662,10 @@ class Call GRPC_FINAL {
     call_hook_->PerformOpsOnCall(ops, this);
   }
 
-  grpc_call* call() { return call_; }
-  CompletionQueue* cq() { return cq_; }
+  grpc_call* call() const { return call_; }
+  CompletionQueue* cq() const { return cq_; }
 
-  int max_message_size() { return max_message_size_; }
+  int max_message_size() const { return max_message_size_; }
 
  private:
   CallHook* call_hook_;
diff --git a/include/grpc++/impl/codegen/completion_queue.h b/include/grpc++/impl/codegen/completion_queue.h
index 03009e0561d..78bc5ca481c 100644
--- a/include/grpc++/impl/codegen/completion_queue.h
+++ b/include/grpc++/impl/codegen/completion_queue.h
@@ -68,8 +68,10 @@ template <class R>
 class ServerReader;
 template <class W>
 class ServerWriter;
+namespace internal {
 template <class W, class R>
-class ServerReaderWriter;
+class ServerReaderWriterBody;
+}
 template <class ServiceType, class RequestType, class ResponseType>
 class RpcMethodHandler;
 template <class ServiceType, class RequestType, class ResponseType>
@@ -178,15 +180,15 @@ class CompletionQueue : private GrpcLibraryCodegen {
   template <class W>
   friend class ::grpc::ServerWriter;
   template <class W, class R>
-  friend class ::grpc::ServerReaderWriter;
+  friend class ::grpc::internal::ServerReaderWriterBody;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ClientStreamingHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ServerStreamingHandler;
-  template <class ServiceType, class RequestType, class ResponseType>
-  friend class BidiStreamingHandler;
+  template <class Streamer, bool WriteNeeded>
+  friend class TemplatedBidiStreamingHandler;
   friend class UnknownMethodHandler;
   friend class ::grpc::Server;
   friend class ::grpc::ServerContext;
diff --git a/include/grpc++/impl/codegen/method_handler_impl.h b/include/grpc++/impl/codegen/method_handler_impl.h
index 2f4be644bae..d989263252d 100644
--- a/include/grpc++/impl/codegen/method_handler_impl.h
+++ b/include/grpc++/impl/codegen/method_handler_impl.h
@@ -167,20 +167,22 @@ class ServerStreamingHandler : public MethodHandler {
 };
 
 // A wrapper class of an application provided bidi-streaming handler.
-template <class ServiceType, class RequestType, class ResponseType>
-class BidiStreamingHandler : public MethodHandler {
+// This also applies to server-streamed implementation of a unary method
+// with the additional requirement that such methods must have done a
+// write for status to be ok
+// Since this is used by more than 1 class, the service is not passed in.
+// Instead, it is expected to be an implicitly-captured argument of func
+// (through bind or something along those lines)
+template <class Streamer, bool WriteNeeded>
+class TemplatedBidiStreamingHandler : public MethodHandler {
  public:
-  BidiStreamingHandler(
-      std::function<Status(ServiceType*, ServerContext*,
-                           ServerReaderWriter<ResponseType, RequestType>*)>
-          func,
-      ServiceType* service)
-      : func_(func), service_(service) {}
+  TemplatedBidiStreamingHandler(
+      std::function<Status(ServerContext*, Streamer*)> func)
+      : func_(func), write_needed_(WriteNeeded) {}
 
   void RunHandler(const HandlerParameter& param) GRPC_FINAL {
-    ServerReaderWriter<ResponseType, RequestType> stream(param.call,
-                                                         param.server_context);
-    Status status = func_(service_, param.server_context, &stream);
+    Streamer stream(param.call, param.server_context);
+    Status status = func_(param.server_context, &stream);
 
     CallOpSet<CallOpSendInitialMetadata, CallOpServerSendStatus> ops;
     if (!param.server_context->sent_initial_metadata_) {
@@ -189,6 +191,12 @@ class BidiStreamingHandler : public MethodHandler {
       if (param.server_context->compression_level_set()) {
         ops.set_compression_level(param.server_context->compression_level());
       }
+      if (write_needed_ && status.ok()) {
+        // If we needed a write but never did one, we need to mark the
+        // status as a fail
+        status = Status(StatusCode::INTERNAL,
+                        "Service did not provide response message");
+      }
     }
     ops.ServerSendStatus(param.server_context->trailing_metadata_, status);
     param.call->PerformOps(&ops);
@@ -196,10 +204,36 @@ class BidiStreamingHandler : public MethodHandler {
   }
 
  private:
-  std::function<Status(ServiceType*, ServerContext*,
-                       ServerReaderWriter<ResponseType, RequestType>*)>
-      func_;
-  ServiceType* service_;
+  std::function<Status(ServerContext*, Streamer*)> func_;
+  const bool write_needed_;
+};
+
+template <class ServiceType, class RequestType, class ResponseType>
+class BidiStreamingHandler
+    : public TemplatedBidiStreamingHandler<
+          ServerReaderWriter<ResponseType, RequestType>, false> {
+ public:
+  BidiStreamingHandler(
+      std::function<Status(ServiceType*, ServerContext*,
+                           ServerReaderWriter<ResponseType, RequestType>*)>
+          func,
+      ServiceType* service)
+      : TemplatedBidiStreamingHandler<
+            ServerReaderWriter<ResponseType, RequestType>, false>(std::bind(
+            func, service, std::placeholders::_1, std::placeholders::_2)) {}
+};
+
+template <class RequestType, class ResponseType>
+class StreamedUnaryHandler
+    : public TemplatedBidiStreamingHandler<
+          ServerUnaryStreamer<RequestType, ResponseType>, true> {
+ public:
+  explicit StreamedUnaryHandler(
+      std::function<Status(ServerContext*,
+                           ServerUnaryStreamer<RequestType, ResponseType>*)>
+          func)
+      : TemplatedBidiStreamingHandler<
+            ServerUnaryStreamer<RequestType, ResponseType>, true>(func) {}
 };
 
 // Handle unknown method by returning UNIMPLEMENTED error.
diff --git a/include/grpc++/impl/codegen/rpc_method.h b/include/grpc++/impl/codegen/rpc_method.h
index 39cb4f75dfe..48974280747 100644
--- a/include/grpc++/impl/codegen/rpc_method.h
+++ b/include/grpc++/impl/codegen/rpc_method.h
@@ -60,11 +60,12 @@ class RpcMethod {
 
   const char* name() const { return name_; }
   RpcType method_type() const { return method_type_; }
+  void SetMethodType(RpcType type) { method_type_ = type; }
   void* channel_tag() const { return channel_tag_; }
 
  private:
   const char* const name_;
-  const RpcType method_type_;
+  RpcType method_type_;
   void* const channel_tag_;
 };
 
diff --git a/include/grpc++/impl/codegen/rpc_service_method.h b/include/grpc++/impl/codegen/rpc_service_method.h
index 8b1f026c912..52124fba0b8 100644
--- a/include/grpc++/impl/codegen/rpc_service_method.h
+++ b/include/grpc++/impl/codegen/rpc_service_method.h
@@ -82,6 +82,7 @@ class RpcServiceMethod : public RpcMethod {
   // if MethodHandler is nullptr, then this is an async method
   MethodHandler* handler() const { return handler_.get(); }
   void ResetHandler() { handler_.reset(); }
+  void SetHandler(MethodHandler* handler) { handler_.reset(handler); }
 
  private:
   void* server_tag_;
diff --git a/include/grpc++/impl/codegen/server_context.h b/include/grpc++/impl/codegen/server_context.h
index c9d1f4d69e9..379c9f7cf8c 100644
--- a/include/grpc++/impl/codegen/server_context.h
+++ b/include/grpc++/impl/codegen/server_context.h
@@ -65,8 +65,10 @@ template <class R>
 class ServerReader;
 template <class W>
 class ServerWriter;
+namespace internal {
 template <class W, class R>
-class ServerReaderWriter;
+class ServerReaderWriterBody;
+}
 template <class ServiceType, class RequestType, class ResponseType>
 class RpcMethodHandler;
 template <class ServiceType, class RequestType, class ResponseType>
@@ -187,15 +189,15 @@ class ServerContext {
   template <class W>
   friend class ::grpc::ServerWriter;
   template <class W, class R>
-  friend class ::grpc::ServerReaderWriter;
+  friend class ::grpc::internal::ServerReaderWriterBody;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ClientStreamingHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class ServerStreamingHandler;
-  template <class ServiceType, class RequestType, class ResponseType>
-  friend class BidiStreamingHandler;
+  template <class Streamer, bool WriteNeeded>
+  friend class TemplatedBidiStreamingHandler;
   friend class UnknownMethodHandler;
   friend class ::grpc::ClientContext;
 
diff --git a/include/grpc++/impl/codegen/service_type.h b/include/grpc++/impl/codegen/service_type.h
index c19dfc7d45f..72b22253128 100644
--- a/include/grpc++/impl/codegen/service_type.h
+++ b/include/grpc++/impl/codegen/service_type.h
@@ -147,6 +147,17 @@ class Service {
     methods_[index].reset();
   }
 
+  void MarkMethodStreamedUnary(int index,
+                               MethodHandler* streamed_unary_method) {
+    GPR_CODEGEN_ASSERT(methods_[index] && methods_[index]->handler() &&
+                       "Cannot mark an async or generic method Streamed Unary");
+    methods_[index]->SetHandler(streamed_unary_method);
+
+    // From the server's point of view, streamed unary is a special
+    // case of BIDI_STREAMING that has 1 read and 1 write, in that order.
+    methods_[index]->SetMethodType(::grpc::RpcMethod::BIDI_STREAMING);
+  }
+
  private:
   friend class Server;
   friend class ServerInterface;
diff --git a/include/grpc++/impl/codegen/sync_stream.h b/include/grpc++/impl/codegen/sync_stream.h
index 7601ceae92d..e1d4660ae77 100644
--- a/include/grpc++/impl/codegen/sync_stream.h
+++ b/include/grpc++/impl/codegen/sync_stream.h
@@ -79,6 +79,9 @@ class ReaderInterface {
  public:
   virtual ~ReaderInterface() {}
 
+  /// Upper bound on the next message size available for reading on this stream
+  virtual bool NextMessageSize(uint32_t* sz) = 0;
+
   /// Blocking read a message and parse to \a msg. Returns \a true on success.
   /// This is thread-safe with respect to \a Write or \WritesDone methods on
   /// the same stream. It should not be called concurrently with another \a
@@ -157,6 +160,11 @@ class ClientReader GRPC_FINAL : public ClientReaderInterface<R> {
     cq_.Pluck(&ops);  /// status ignored
   }
 
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    *sz = call_.max_message_size();
+    return true;
+  }
+
   bool Read(R* msg) GRPC_OVERRIDE {
     CallOpSet<CallOpRecvInitialMetadata, CallOpRecvMessage<R>> ops;
     if (!context_->initial_metadata_received_) {
@@ -302,6 +310,11 @@ class ClientReaderWriter GRPC_FINAL : public ClientReaderWriterInterface<W, R> {
     cq_.Pluck(&ops);  // status ignored
   }
 
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    *sz = call_.max_message_size();
+    return true;
+  }
+
   bool Read(R* msg) GRPC_OVERRIDE {
     CallOpSet<CallOpRecvInitialMetadata, CallOpRecvMessage<R>> ops;
     if (!context_->initial_metadata_received_) {
@@ -369,6 +382,11 @@ class ServerReader GRPC_FINAL : public ServerReaderInterface<R> {
     call_->cq()->Pluck(&ops);
   }
 
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    *sz = call_->max_message_size();
+    return true;
+  }
+
   bool Read(R* msg) GRPC_OVERRIDE {
     CallOpSet<CallOpRecvMessage<R>> ops;
     ops.RecvMessage(msg);
@@ -434,12 +452,15 @@ class ServerReaderWriterInterface : public ServerStreamingInterface,
                                     public WriterInterface<W>,
                                     public ReaderInterface<R> {};
 
+// Actual implementation of bi-directional streaming
+namespace internal {
 template <class W, class R>
-class ServerReaderWriter GRPC_FINAL : public ServerReaderWriterInterface<W, R> {
+class ServerReaderWriterBody GRPC_FINAL {
  public:
-  ServerReaderWriter(Call* call, ServerContext* ctx) : call_(call), ctx_(ctx) {}
+  ServerReaderWriterBody(Call* call, ServerContext* ctx)
+      : call_(call), ctx_(ctx) {}
 
-  void SendInitialMetadata() GRPC_OVERRIDE {
+  void SendInitialMetadata() {
     GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
 
     CallOpSet<CallOpSendInitialMetadata> ops;
@@ -453,15 +474,19 @@ class ServerReaderWriter GRPC_FINAL : public ServerReaderWriterInterface<W, R> {
     call_->cq()->Pluck(&ops);
   }
 
-  bool Read(R* msg) GRPC_OVERRIDE {
+  bool NextMessageSize(uint32_t* sz) {
+    *sz = call_->max_message_size();
+    return true;
+  }
+
+  bool Read(R* msg) {
     CallOpSet<CallOpRecvMessage<R>> ops;
     ops.RecvMessage(msg);
     call_->PerformOps(&ops);
     return call_->cq()->Pluck(&ops) && ops.got_message;
   }
 
-  using WriterInterface<W>::Write;
-  bool Write(const W& msg, const WriteOptions& options) GRPC_OVERRIDE {
+  bool Write(const W& msg, const WriteOptions& options) {
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> ops;
     if (!ops.SendMessage(msg, options).ok()) {
       return false;
@@ -482,6 +507,76 @@ class ServerReaderWriter GRPC_FINAL : public ServerReaderWriterInterface<W, R> {
   Call* const call_;
   ServerContext* const ctx_;
 };
+}
+
+// class to represent the user API for a bidirectional streaming call
+template <class W, class R>
+class ServerReaderWriter GRPC_FINAL : public ServerReaderWriterInterface<W, R> {
+ public:
+  ServerReaderWriter(Call* call, ServerContext* ctx) : body_(call, ctx) {}
+
+  void SendInitialMetadata() GRPC_OVERRIDE { body_.SendInitialMetadata(); }
+
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    return body_.NextMessageSize(sz);
+  }
+
+  bool Read(R* msg) GRPC_OVERRIDE { return body_.Read(msg); }
+
+  using WriterInterface<W>::Write;
+  bool Write(const W& msg, const WriteOptions& options) GRPC_OVERRIDE {
+    return body_.Write(msg, options);
+  }
+
+ private:
+  internal::ServerReaderWriterBody<W, R> body_;
+};
+
+/// A class to represent a flow-controlled unary call. This is something
+/// of a hybrid between conventional unary and streaming. This is invoked
+/// through a unary call on the client side, but the server responds to it
+/// as though it were a single-ping-pong streaming call. The server can use
+/// the \a NextMessageSize method to determine an upper-bound on the size of
+/// the message.
+/// A key difference relative to streaming: ServerUnaryStreamer
+///  must have exactly 1 Read and exactly 1 Write, in that order, to function
+/// correctly. Otherwise, the RPC is in error.
+template <class RequestType, class ResponseType>
+class ServerUnaryStreamer GRPC_FINAL
+    : public ServerReaderWriterInterface<ResponseType, RequestType> {
+ public:
+  ServerUnaryStreamer(Call* call, ServerContext* ctx)
+      : body_(call, ctx), read_done_(false), write_done_(false) {}
+
+  void SendInitialMetadata() GRPC_OVERRIDE { body_.SendInitialMetadata(); }
+
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    return body_.NextMessageSize(sz);
+  }
+
+  bool Read(RequestType* request) GRPC_OVERRIDE {
+    if (read_done_) {
+      return false;
+    }
+    read_done_ = true;
+    return body_.Read(request);
+  }
+
+  using WriterInterface<ResponseType>::Write;
+  bool Write(const ResponseType& response,
+             const WriteOptions& options) GRPC_OVERRIDE {
+    if (write_done_ || !read_done_) {
+      return false;
+    }
+    write_done_ = true;
+    return body_.Write(response, options);
+  }
+
+ private:
+  internal::ServerReaderWriterBody<ResponseType, RequestType> body_;
+  bool read_done_;
+  bool write_done_;
+};
 
 }  // namespace grpc
 
diff --git a/src/compiler/cpp_generator.cc b/src/compiler/cpp_generator.cc
index c386115ec20..d0c35ea1ab3 100644
--- a/src/compiler/cpp_generator.cc
+++ b/src/compiler/cpp_generator.cc
@@ -130,6 +130,7 @@ grpc::string GetHeaderIncludes(File *file, const Parameters &params) {
     static const char *headers_strs[] = {
         "grpc++/impl/codegen/async_stream.h",
         "grpc++/impl/codegen/async_unary_call.h",
+        "grpc++/impl/codegen/method_handler_impl.h",
         "grpc++/impl/codegen/proto_utils.h",
         "grpc++/impl/codegen/rpc_method.h",
         "grpc++/impl/codegen/service_type.h",
@@ -604,6 +605,57 @@ void PrintHeaderServerMethodAsync(Printer *printer, const Method *method,
   printer->Print(*vars, "};\n");
 }
 
+void PrintHeaderServerMethodStreamedUnary(
+    Printer *printer, const Method *method,
+    std::map<grpc::string, grpc::string> *vars) {
+  (*vars)["Method"] = method->name();
+  (*vars)["Request"] = method->input_type_name();
+  (*vars)["Response"] = method->output_type_name();
+  if (method->NoStreaming()) {
+    printer->Print(*vars, "template <class BaseClass>\n");
+    printer->Print(*vars,
+                   "class WithStreamedUnaryMethod_$Method$ : "
+                   "public BaseClass {\n");
+    printer->Print(
+        " private:\n"
+        "  void BaseClassMustBeDerivedFromService(const Service *service) "
+        "{}\n");
+    printer->Print(" public:\n");
+    printer->Indent();
+    printer->Print(*vars,
+                   "WithStreamedUnaryMethod_$Method$() {\n"
+                   "  ::grpc::Service::MarkMethodStreamedUnary($Idx$,\n"
+                   "    new ::grpc::StreamedUnaryHandler< $Request$, "
+                   "$Response$>(std::bind"
+                   "(&WithStreamedUnaryMethod_$Method$<BaseClass>::"
+                   "Streamed$Method$, this, std::placeholders::_1, "
+                   "std::placeholders::_2)));\n"
+                   "}\n");
+    printer->Print(*vars,
+                   "~WithStreamedUnaryMethod_$Method$() GRPC_OVERRIDE {\n"
+                   "  BaseClassMustBeDerivedFromService(this);\n"
+                   "}\n");
+    printer->Print(
+        *vars,
+        "// disable regular version of this method\n"
+        "::grpc::Status $Method$("
+        "::grpc::ServerContext* context, const $Request$* request, "
+        "$Response$* response) GRPC_FINAL GRPC_OVERRIDE {\n"
+        "  abort();\n"
+        "  return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, \"\");\n"
+        "}\n");
+    printer->Print(*vars,
+                   "// replace default version of method with streamed unary\n"
+                   "virtual ::grpc::Status Streamed$Method$("
+                   "::grpc::ServerContext* context, "
+                   "::grpc::ServerUnaryStreamer< "
+                   "$Request$,$Response$>* server_unary_streamer)"
+                   " = 0;\n");
+    printer->Outdent();
+    printer->Print(*vars, "};\n");
+  }
+}
+
 void PrintHeaderServerMethodGeneric(
     Printer *printer, const Method *method,
     std::map<grpc::string, grpc::string> *vars) {
@@ -770,6 +822,28 @@ void PrintHeaderService(Printer *printer, const Service *service,
     PrintHeaderServerMethodGeneric(printer, service->method(i).get(), vars);
   }
 
+  // Server side - Streamed Unary
+  for (int i = 0; i < service->method_count(); ++i) {
+    (*vars)["Idx"] = as_string(i);
+    PrintHeaderServerMethodStreamedUnary(printer, service->method(i).get(),
+                                         vars);
+  }
+
+  printer->Print("typedef ");
+  for (int i = 0; i < service->method_count(); ++i) {
+    (*vars)["method_name"] = service->method(i).get()->name();
+    if (service->method(i)->NoStreaming()) {
+      printer->Print(*vars, "WithStreamedUnaryMethod_$method_name$<");
+    }
+  }
+  printer->Print("Service");
+  for (int i = 0; i < service->method_count(); ++i) {
+    if (service->method(i)->NoStreaming()) {
+      printer->Print(" >");
+    }
+  }
+  printer->Print(" StreamedUnaryService;\n");
+
   printer->Outdent();
   printer->Print("};\n");
   printer->Print(service->GetTrailingComments().c_str());
@@ -1080,6 +1154,9 @@ void PrintSourceService(Printer *printer, const Service *service,
     (*vars)["Idx"] = as_string(i);
     if (method->NoStreaming()) {
       (*vars)["StreamingType"] = "NORMAL_RPC";
+      // NOTE: There is no reason to consider streamed-unary as a separate
+      // category here since this part is setting up the client-side stub
+      // and this appears as a NORMAL_RPC from the client-side.
     } else if (method->ClientOnlyStreaming()) {
       (*vars)["StreamingType"] = "CLIENT_STREAMING";
     } else if (method->ServerOnlyStreaming()) {
diff --git a/src/ruby/lib/grpc/generic/rpc_server.rb b/src/ruby/lib/grpc/generic/rpc_server.rb
index 8ea798dce06..da0f6503db3 100644
--- a/src/ruby/lib/grpc/generic/rpc_server.rb
+++ b/src/ruby/lib/grpc/generic/rpc_server.rb
@@ -31,113 +31,10 @@ require_relative '../grpc'
 require_relative 'active_call'
 require_relative 'service'
 require 'thread'
+require 'concurrent'
 
 # GRPC contains the General RPC module.
 module GRPC
-  # Pool is a simple thread pool.
-  class Pool
-    # Default keep alive period is 1s
-    DEFAULT_KEEP_ALIVE = 1
-
-    def initialize(size, keep_alive: DEFAULT_KEEP_ALIVE)
-      fail 'pool size must be positive' unless size > 0
-      @jobs = Queue.new
-      @size = size
-      @stopped = false
-      @stop_mutex = Mutex.new # needs to be held when accessing @stopped
-      @stop_cond = ConditionVariable.new
-      @workers = []
-      @keep_alive = keep_alive
-    end
-
-    # Returns the number of jobs waiting
-    def jobs_waiting
-      @jobs.size
-    end
-
-    # Runs the given block on the queue with the provided args.
-    #
-    # @param args the args passed blk when it is called
-    # @param blk the block to call
-    def schedule(*args, &blk)
-      return if blk.nil?
-      @stop_mutex.synchronize do
-        if @stopped
-          GRPC.logger.warn('did not schedule job, already stopped')
-          return
-        end
-        GRPC.logger.info('schedule another job')
-        @jobs << [blk, args]
-      end
-    end
-
-    # Starts running the jobs in the thread pool.
-    def start
-      @stop_mutex.synchronize do
-        fail 'already stopped' if @stopped
-      end
-      until @workers.size == @size.to_i
-        next_thread = Thread.new do
-          catch(:exit) do  # allows { throw :exit } to kill a thread
-            loop_execute_jobs
-          end
-          remove_current_thread
-        end
-        @workers << next_thread
-      end
-    end
-
-    # Stops the jobs in the pool
-    def stop
-      GRPC.logger.info('stopping, will wait for all the workers to exit')
-      @workers.size.times { schedule { throw :exit } }
-      @stop_mutex.synchronize do  # wait @keep_alive for works to stop
-        @stopped = true
-        @stop_cond.wait(@stop_mutex, @keep_alive) if @workers.size > 0
-      end
-      forcibly_stop_workers
-      GRPC.logger.info('stopped, all workers are shutdown')
-    end
-
-    protected
-
-    # Forcibly shutdown any threads that are still alive.
-    def forcibly_stop_workers
-      return unless @workers.size > 0
-      GRPC.logger.info("forcibly terminating #{@workers.size} worker(s)")
-      @workers.each do |t|
-        next unless t.alive?
-        begin
-          t.exit
-        rescue StandardError => e
-          GRPC.logger.warn('error while terminating a worker')
-          GRPC.logger.warn(e)
-        end
-      end
-    end
-
-    # removes the threads from workers, and signal when all the
-    # threads are complete.
-    def remove_current_thread
-      @stop_mutex.synchronize do
-        @workers.delete(Thread.current)
-        @stop_cond.signal if @workers.size.zero?
-      end
-    end
-
-    def loop_execute_jobs
-      loop do
-        begin
-          blk, args = @jobs.pop
-          blk.call(*args)
-        rescue StandardError => e
-          GRPC.logger.warn('Error in worker thread')
-          GRPC.logger.warn(e)
-        end
-      end
-    end
-  end
-
   # RpcServer hosts a number of services and makes them available on the
   # network.
   class RpcServer
@@ -147,11 +44,14 @@ module GRPC
 
     def_delegators :@server, :add_http2_port
 
-    # Default thread pool size is 3
-    DEFAULT_POOL_SIZE = 3
+    # Default max size of the thread pool size is 100
+    DEFAULT_MAX_POOL_SIZE = 100
+
+    # Default minimum size of the thread pool is 5
+    DEFAULT_MIN_POOL_SIZE = 5
 
-    # Default max_waiting_requests size is 20
-    DEFAULT_MAX_WAITING_REQUESTS = 20
+    # Default max_waiting_requests size is 60
+    DEFAULT_MAX_WAITING_REQUESTS = 60
 
     # Default poll period is 1s
     DEFAULT_POLL_PERIOD = 1
@@ -174,8 +74,8 @@ module GRPC
     # There are some specific keyword args used to configure the RpcServer
     # instance.
     #
-    # * pool_size: the size of the thread pool the server uses to run its
-    # threads
+    # * pool_size: the maximum size of the thread pool that the server's
+    # thread pool can reach.
     #
     # * max_waiting_requests: the maximum number of requests that are not
     # being handled to allow. When this limit is exceeded, the server responds
@@ -191,7 +91,8 @@ module GRPC
     #
     # * server_args:
     # A server arguments hash to be passed down to the underlying core server
-    def initialize(pool_size:DEFAULT_POOL_SIZE,
+    def initialize(pool_size:DEFAULT_MAX_POOL_SIZE,
+                   min_pool_size:DEFAULT_MIN_POOL_SIZE,
                    max_waiting_requests:DEFAULT_MAX_WAITING_REQUESTS,
                    poll_period:DEFAULT_POLL_PERIOD,
                    connect_md_proc:nil,
@@ -199,8 +100,12 @@ module GRPC
       @connect_md_proc = RpcServer.setup_connect_md_proc(connect_md_proc)
       @max_waiting_requests = max_waiting_requests
       @poll_period = poll_period
-      @pool_size = pool_size
-      @pool = Pool.new(@pool_size)
+
+      @pool = Concurrent::ThreadPoolExecutor.new(
+        min_threads: [min_pool_size, pool_size].min,
+        max_threads: pool_size,
+        max_queue: max_waiting_requests,
+        fallback_policy: :discard)
       @run_cond = ConditionVariable.new
       @run_mutex = Mutex.new
       # running_state can take 4 values: :not_started, :running, :stopping, and
@@ -221,7 +126,8 @@ module GRPC
       end
       deadline = from_relative_time(@poll_period)
       @server.close(deadline)
-      @pool.stop
+      @pool.shutdown
+      @pool.wait_for_termination
     end
 
     def running_state
@@ -318,7 +224,6 @@ module GRPC
     def run
       @run_mutex.synchronize do
         fail 'cannot run without registering services' if rpc_descs.size.zero?
-        @pool.start
         @server.start
         transition_running_state(:running)
         @run_cond.broadcast
@@ -330,9 +235,11 @@ module GRPC
 
     # Sends RESOURCE_EXHAUSTED if there are too many unprocessed jobs
     def available?(an_rpc)
-      jobs_count, max = @pool.jobs_waiting, @max_waiting_requests
+      jobs_count, max = @pool.queue_length, @pool.max_queue
       GRPC.logger.info("waiting: #{jobs_count}, max: #{max}")
-      return an_rpc if @pool.jobs_waiting <= @max_waiting_requests
+
+      # remaining capacity for ThreadPoolExecutors is -1 if unbounded
+      return an_rpc if @pool.remaining_capacity != 0
       GRPC.logger.warn("NOT AVAILABLE: too many jobs_waiting: #{an_rpc}")
       noop = proc { |x| x }
 
@@ -368,7 +275,7 @@ module GRPC
           break if (!an_rpc.nil?) && an_rpc.call.nil?
           active_call = new_active_server_call(an_rpc)
           unless active_call.nil?
-            @pool.schedule(active_call) do |ac|
+            @pool.post(active_call) do |ac|
               c, mth = ac
               begin
                 rpc_descs[mth].run_server_method(c, rpc_handlers[mth])
diff --git a/src/ruby/spec/generic/rpc_server_pool_spec.rb b/src/ruby/spec/generic/rpc_server_pool_spec.rb
deleted file mode 100644
index b67008de486..00000000000
--- a/src/ruby/spec/generic/rpc_server_pool_spec.rb
+++ /dev/null
@@ -1,138 +0,0 @@
-# Copyright 2015, Google Inc.
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google Inc. nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-require 'grpc'
-
-describe GRPC::Pool do
-  Pool = GRPC::Pool
-
-  describe '#new' do
-    it 'raises if a non-positive size is used' do
-      expect { Pool.new(0) }.to raise_error
-      expect { Pool.new(-1) }.to raise_error
-      expect { Pool.new(Object.new) }.to raise_error
-    end
-
-    it 'is constructed OK with a positive size' do
-      expect { Pool.new(1) }.not_to raise_error
-    end
-  end
-
-  describe '#jobs_waiting' do
-    it 'at start, it is zero' do
-      p = Pool.new(1)
-      expect(p.jobs_waiting).to be(0)
-    end
-
-    it 'it increases, with each scheduled job if the pool is not running' do
-      p = Pool.new(1)
-      job = proc {}
-      expect(p.jobs_waiting).to be(0)
-      5.times do |i|
-        p.schedule(&job)
-        expect(p.jobs_waiting).to be(i + 1)
-      end
-    end
-
-    it 'it decreases as jobs are run' do
-      p = Pool.new(1)
-      job = proc {}
-      expect(p.jobs_waiting).to be(0)
-      3.times do
-        p.schedule(&job)
-      end
-      p.start
-      sleep 2
-      expect(p.jobs_waiting).to be(0)
-    end
-  end
-
-  describe '#schedule' do
-    it 'return if the pool is already stopped' do
-      p = Pool.new(1)
-      p.stop
-      job = proc {}
-      expect { p.schedule(&job) }.to_not raise_error
-    end
-
-    it 'adds jobs that get run by the pool' do
-      p = Pool.new(1)
-      p.start
-      o, q = Object.new, Queue.new
-      job = proc { q.push(o) }
-      p.schedule(&job)
-      expect(q.pop).to be(o)
-      p.stop
-    end
-  end
-
-  describe '#stop' do
-    it 'works when there are no scheduled tasks' do
-      p = Pool.new(1)
-      expect { p.stop }.not_to raise_error
-    end
-
-    it 'stops jobs when there are long running jobs' do
-      p = Pool.new(1)
-      p.start
-      o, q = Object.new, Queue.new
-      job = proc do
-        sleep(5)  # long running
-        q.push(o)
-      end
-      p.schedule(&job)
-      sleep(1)  # should ensure the long job gets scheduled
-      expect { p.stop }.not_to raise_error
-    end
-  end
-
-  describe '#start' do
-    it 'runs pre-scheduled jobs' do
-      p = Pool.new(2)
-      o, q = Object.new, Queue.new
-      n = 5  # arbitrary
-      n.times { p.schedule(o, &q.method(:push)) }
-      p.start
-      n.times { expect(q.pop).to be(o) }
-      p.stop
-    end
-
-    it 'runs jobs as they are scheduled ' do
-      p = Pool.new(2)
-      o, q = Object.new, Queue.new
-      p.start
-      n = 5  # arbitrary
-      n.times do
-        p.schedule(o, &q.method(:push))
-        expect(q.pop).to be(o)
-      end
-      p.stop
-    end
-  end
-end
diff --git a/src/ruby/spec/generic/rpc_server_spec.rb b/src/ruby/spec/generic/rpc_server_spec.rb
index 31157cf161e..d362e48deee 100644
--- a/src/ruby/spec/generic/rpc_server_spec.rb
+++ b/src/ruby/spec/generic/rpc_server_spec.rb
@@ -395,9 +395,9 @@ describe GRPC::RpcServer do
       it 'should return RESOURCE_EXHAUSTED on too many jobs', server: true do
         opts = {
           server_args: { a_channel_arg: 'an_arg' },
-          pool_size: 1,
+          pool_size: 2,
           poll_period: 1,
-          max_waiting_requests: 0
+          max_waiting_requests: 1
         }
         alt_srv = RpcServer.new(**opts)
         alt_srv.handle(SlowService)
@@ -406,24 +406,23 @@ describe GRPC::RpcServer do
         t = Thread.new { alt_srv.run }
         alt_srv.wait_till_running
         req = EchoMsg.new
-        n = 5  # arbitrary, use as many to ensure the server pool is exceeded
+        n = 20 # arbitrary, use as many to ensure the server pool is exceeded
         threads = []
-        one_failed_as_unavailable = false
+        bad_status_code = nil
         n.times do
           threads << Thread.new do
             stub = SlowStub.new(alt_host, :this_channel_is_insecure)
             begin
               stub.an_rpc(req)
             rescue GRPC::BadStatus => e
-              one_failed_as_unavailable =
-                e.code == StatusCodes::RESOURCE_EXHAUSTED
+              bad_status_code = e.code
             end
           end
         end
         threads.each(&:join)
         alt_srv.stop
         t.join
-        expect(one_failed_as_unavailable).to be(true)
+        expect(bad_status_code).to be(StatusCodes::RESOURCE_EXHAUSTED)
       end
     end
 
diff --git a/templates/grpc.gemspec.template b/templates/grpc.gemspec.template
index f95adaf30fa..75a6054b81e 100644
--- a/templates/grpc.gemspec.template
+++ b/templates/grpc.gemspec.template
@@ -31,6 +31,7 @@
 
     s.add_dependency 'google-protobuf', '~> 3.0'
     s.add_dependency 'googleauth',      '~> 0.5.1'
+    s.add_dependency 'concurrent-ruby'
 
     s.add_development_dependency 'bundler',            '~> 1.9'
     s.add_development_dependency 'facter',             '~> 2.4'
diff --git a/test/cpp/codegen/compiler_test_golden b/test/cpp/codegen/compiler_test_golden
index ef3d1aaa510..7b0fd6ce804 100644
--- a/test/cpp/codegen/compiler_test_golden
+++ b/test/cpp/codegen/compiler_test_golden
@@ -43,6 +43,7 @@
 
 #include <grpc++/impl/codegen/async_stream.h>
 #include <grpc++/impl/codegen/async_unary_call.h>
+#include <grpc++/impl/codegen/method_handler_impl.h>
 #include <grpc++/impl/codegen/proto_utils.h>
 #include <grpc++/impl/codegen/rpc_method.h>
 #include <grpc++/impl/codegen/service_type.h>
@@ -206,6 +207,27 @@ class ServiceA GRPC_FINAL {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
   };
+  template <class BaseClass>
+  class WithStreamedUnaryMethod_MethodA1 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithStreamedUnaryMethod_MethodA1() {
+      ::grpc::Service::MarkMethodStreamedUnary(0,
+        new ::grpc::StreamedUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(std::bind(&WithStreamedUnaryMethod_MethodA1<BaseClass>::StreamedMethodA1, this, std::placeholders::_1, std::placeholders::_2)));
+    }
+    ~WithStreamedUnaryMethod_MethodA1() GRPC_OVERRIDE {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable regular version of this method
+    ::grpc::Status MethodA1(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::testing::Response* response) GRPC_FINAL GRPC_OVERRIDE {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    // replace default version of method with streamed unary
+    virtual ::grpc::Status StreamedMethodA1(::grpc::ServerContext* context, ::grpc::ServerUnaryStreamer< ::grpc::testing::Request,::grpc::testing::Response>* server_unary_streamer) = 0;
+  };
+  typedef WithStreamedUnaryMethod_MethodA1<Service > StreamedUnaryService;
 };
 
 // ServiceB leading comment 1
@@ -284,6 +306,27 @@ class ServiceB GRPC_FINAL {
       return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
     }
   };
+  template <class BaseClass>
+  class WithStreamedUnaryMethod_MethodB1 : public BaseClass {
+   private:
+    void BaseClassMustBeDerivedFromService(const Service *service) {}
+   public:
+    WithStreamedUnaryMethod_MethodB1() {
+      ::grpc::Service::MarkMethodStreamedUnary(0,
+        new ::grpc::StreamedUnaryHandler< ::grpc::testing::Request, ::grpc::testing::Response>(std::bind(&WithStreamedUnaryMethod_MethodB1<BaseClass>::StreamedMethodB1, this, std::placeholders::_1, std::placeholders::_2)));
+    }
+    ~WithStreamedUnaryMethod_MethodB1() GRPC_OVERRIDE {
+      BaseClassMustBeDerivedFromService(this);
+    }
+    // disable regular version of this method
+    ::grpc::Status MethodB1(::grpc::ServerContext* context, const ::grpc::testing::Request* request, ::grpc::testing::Response* response) GRPC_FINAL GRPC_OVERRIDE {
+      abort();
+      return ::grpc::Status(::grpc::StatusCode::UNIMPLEMENTED, "");
+    }
+    // replace default version of method with streamed unary
+    virtual ::grpc::Status StreamedMethodB1(::grpc::ServerContext* context, ::grpc::ServerUnaryStreamer< ::grpc::testing::Request,::grpc::testing::Response>* server_unary_streamer) = 0;
+  };
+  typedef WithStreamedUnaryMethod_MethodB1<Service > StreamedUnaryService;
 };
 // ServiceB trailing comment 1
 
diff --git a/test/cpp/end2end/hybrid_end2end_test.cc b/test/cpp/end2end/hybrid_end2end_test.cc
index 7e0c0e8a7ca..a6ea13aa8bd 100644
--- a/test/cpp/end2end/hybrid_end2end_test.cc
+++ b/test/cpp/end2end/hybrid_end2end_test.cc
@@ -199,7 +199,8 @@ class HybridEnd2endTest : public ::testing::Test {
   HybridEnd2endTest() {}
 
   void SetUpServer(::grpc::Service* service1, ::grpc::Service* service2,
-                   AsyncGenericService* generic_service) {
+                   AsyncGenericService* generic_service,
+                   int max_message_size = 0) {
     int port = grpc_pick_unused_port_or_die();
     server_address_ << "localhost:" << port;
 
@@ -217,6 +218,11 @@ class HybridEnd2endTest : public ::testing::Test {
     if (generic_service) {
       builder.RegisterAsyncGenericService(generic_service);
     }
+
+    if (max_message_size != 0) {
+      builder.SetMaxMessageSize(max_message_size);
+    }
+
     // Create a separate cq for each potential handler.
     for (int i = 0; i < 5; i++) {
       cqs_.push_back(builder.AddCompletionQueue(false));
@@ -415,6 +421,83 @@ TEST_F(HybridEnd2endTest, AsyncRequestStreamResponseStream_SyncDupService) {
   request_stream_handler_thread.join();
 }
 
+// Add a second service with one sync streamed unary method.
+class StreamedUnaryDupPkg
+    : public duplicate::EchoTestService::WithStreamedUnaryMethod_Echo<
+          TestServiceImplDupPkg> {
+ public:
+  Status StreamedEcho(ServerContext* context,
+                      ServerUnaryStreamer<EchoRequest, EchoResponse>* stream)
+      GRPC_OVERRIDE {
+    EchoRequest req;
+    EchoResponse resp;
+    uint32_t next_msg_sz;
+    stream->NextMessageSize(&next_msg_sz);
+    gpr_log(GPR_INFO, "Streamed Unary Next Message Size is %u", next_msg_sz);
+    GPR_ASSERT(stream->Read(&req));
+    resp.set_message(req.message() + "_dup");
+    GPR_ASSERT(stream->Write(resp));
+    return Status::OK;
+  }
+};
+
+TEST_F(HybridEnd2endTest,
+       AsyncRequestStreamResponseStream_SyncStreamedUnaryDupService) {
+  typedef EchoTestService::WithAsyncMethod_RequestStream<
+      EchoTestService::WithAsyncMethod_ResponseStream<TestServiceImpl>>
+      SType;
+  SType service;
+  StreamedUnaryDupPkg dup_service;
+  SetUpServer(&service, &dup_service, nullptr, 8192);
+  ResetStub();
+  std::thread response_stream_handler_thread(HandleServerStreaming<SType>,
+                                             &service, cqs_[0].get());
+  std::thread request_stream_handler_thread(HandleClientStreaming<SType>,
+                                            &service, cqs_[1].get());
+  TestAllMethods();
+  SendEchoToDupService();
+  response_stream_handler_thread.join();
+  request_stream_handler_thread.join();
+}
+
+// Add a second service that is fully Streamed Unary
+class FullyStreamedUnaryDupPkg
+    : public duplicate::EchoTestService::StreamedUnaryService {
+ public:
+  Status StreamedEcho(ServerContext* context,
+                      ServerUnaryStreamer<EchoRequest, EchoResponse>* stream)
+      GRPC_OVERRIDE {
+    EchoRequest req;
+    EchoResponse resp;
+    uint32_t next_msg_sz;
+    stream->NextMessageSize(&next_msg_sz);
+    gpr_log(GPR_INFO, "Streamed Unary Next Message Size is %u", next_msg_sz);
+    GPR_ASSERT(stream->Read(&req));
+    resp.set_message(req.message() + "_dup");
+    GPR_ASSERT(stream->Write(resp));
+    return Status::OK;
+  }
+};
+
+TEST_F(HybridEnd2endTest,
+       AsyncRequestStreamResponseStream_SyncFullyStreamedUnaryDupService) {
+  typedef EchoTestService::WithAsyncMethod_RequestStream<
+      EchoTestService::WithAsyncMethod_ResponseStream<TestServiceImpl>>
+      SType;
+  SType service;
+  FullyStreamedUnaryDupPkg dup_service;
+  SetUpServer(&service, &dup_service, nullptr, 8192);
+  ResetStub();
+  std::thread response_stream_handler_thread(HandleServerStreaming<SType>,
+                                             &service, cqs_[0].get());
+  std::thread request_stream_handler_thread(HandleClientStreaming<SType>,
+                                            &service, cqs_[1].get());
+  TestAllMethods();
+  SendEchoToDupService();
+  response_stream_handler_thread.join();
+  request_stream_handler_thread.join();
+}
+
 // Add a second service with one async method.
 TEST_F(HybridEnd2endTest, AsyncRequestStreamResponseStream_AsyncDupService) {
   typedef EchoTestService::WithAsyncMethod_RequestStream<
diff --git a/test/cpp/end2end/mock_test.cc b/test/cpp/end2end/mock_test.cc
index 0ace5d94183..40526271221 100644
--- a/test/cpp/end2end/mock_test.cc
+++ b/test/cpp/end2end/mock_test.cc
@@ -31,6 +31,7 @@
  *
  */
 
+#include <climits>
 #include <thread>
 
 #include <grpc++/channel.h>
@@ -63,6 +64,10 @@ class MockClientReaderWriter GRPC_FINAL
     : public ClientReaderWriterInterface<W, R> {
  public:
   void WaitForInitialMetadata() GRPC_OVERRIDE {}
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    *sz = UINT_MAX;
+    return true;
+  }
   bool Read(R* msg) GRPC_OVERRIDE { return true; }
   bool Write(const W& msg) GRPC_OVERRIDE { return true; }
   bool WritesDone() GRPC_OVERRIDE { return true; }
@@ -74,6 +79,10 @@ class MockClientReaderWriter<EchoRequest, EchoResponse> GRPC_FINAL
  public:
   MockClientReaderWriter() : writes_done_(false) {}
   void WaitForInitialMetadata() GRPC_OVERRIDE {}
+  bool NextMessageSize(uint32_t* sz) GRPC_OVERRIDE {
+    *sz = UINT_MAX;
+    return true;
+  }
   bool Read(EchoResponse* msg) GRPC_OVERRIDE {
     if (writes_done_) return false;
     msg->set_message(last_message_);