1 files changed, 7 insertions, 0 deletions
diff --git a/src/cpp/server/server_builder.cc b/src/cpp/server/server_builder.cc
index f723d4611a..fd97ad082c 100644
--- a/src/cpp/server/server_builder.cc
+++ b/src/cpp/server/server_builder.cc
@@ -38,6 +38,7 @@
 #include <grpc++/impl/service_type.h>
 #include <grpc++/server.h>
 #include <grpc++/thread_pool_interface.h>
+#include <grpc++/fixed_size_thread_pool.h>
 
 namespace grpc {
 
@@ -100,6 +101,12 @@ std::unique_ptr<Server> ServerBuilder::BuildAndStart() {
     thread_pool_ = CreateDefaultThreadPool();
     thread_pool_owned = true;
   }
+  // Async services only, create a thread pool to handle requests to unknown
+  // services.
+  if (!thread_pool_ && !generic_service_ && !async_services_.empty()) {
+    thread_pool_ = new FixedSizeThreadPool(1);
+    thread_pool_owned = true;
+  }
   std::unique_ptr<Server> server(
       new Server(thread_pool_, thread_pool_owned, max_message_size_));
   for (auto cq = cqs_.begin(); cq != cqs_.end(); ++cq) {