Skip scheduling for empty cold creation. (apache#5316)

Author: style95

core/scheduler/src/main/scala/org/apache/openwhisk/core/scheduler/container/ContainerManager.scala

@@ -181,20 +181,22 @@ class ContainerManager(jobManagerFactory: ActorRefFactory => ActorRef,
           }
 
           // handle cold creations
-          ContainerManager
-            .schedule(updatedInvokers, coldCreations.map(_._1), memory)
-            .map { pair =>
-              pair.invokerId match {
-                // an invoker is assigned for the msg
-                case Some(instanceId) =>
-                  creationJobManager ! RegisterCreationJob(pair.msg)
-                  sendCreationContainerToInvoker(messagingProducer, instanceId.instance, pair.msg)
-
-                // if a chosen invoker does not exist, it means it failed to find a matching invoker for the msg.
-                case _ =>
-                  pair.err.foreach(error => sendState(pair.msg, error, error))
+          if (coldCreations.nonEmpty) {
+            ContainerManager
+              .schedule(updatedInvokers, coldCreations.map(_._1), memory)
+              .map { pair =>
+                pair.invokerId match {
+                  // an invoker is assigned for the msg
+                  case Some(instanceId) =>
+                    creationJobManager ! RegisterCreationJob(pair.msg)
+                    sendCreationContainerToInvoker(messagingProducer, instanceId.instance, pair.msg)
+
+                  // if a chosen invoker does not exist, it means it failed to find a matching invoker for the msg.
+                  case _ =>
+                    pair.err.foreach(error => sendState(pair.msg, error, error))
+                }
               }
-            }
+          }
         }
       }
   }

tests/src/test/scala/org/apache/openwhisk/core/scheduler/container/test/ContainerManagerTests.scala

@@ -136,7 +136,7 @@ class ContainerManagerTests
 
   def mockMessaging(receiver: Option[ActorRef] = None): MessagingProvider = {
     val messaging = stub[MessagingProvider]
-    val producer = receiver.map(fakeProducer(_)).getOrElse(stub[MessageProducer])
+    val producer = receiver.map(fakeProducer).getOrElse(stub[MessageProducer])
     val consumer = stub[MessageConsumer]
     (messaging
       .getProducer(_: WhiskConfig, _: Option[ByteSize])(_: Logging, _: ActorSystem))