Automatic passivation for typed sharding, #25512

akka-cluster-sharding-typed/src/main/scala/akka/cluster/sharding/typed/ClusterShardingSettings.scala

@@ -4,8 +4,7 @@
 
 package akka.cluster.sharding.typed
 
-import scala.concurrent.duration.FiniteDuration
-
+import scala.concurrent.duration.{ Duration, FiniteDuration }
 import akka.actor.NoSerializationVerificationNeeded
 import akka.actor.typed.ActorSystem
 import akka.annotation.InternalApi
@@ -42,6 +41,7 @@ object ClusterShardingSettings {
       rememberEntities = untypedSettings.rememberEntities,
       journalPluginId = untypedSettings.journalPluginId,
       snapshotPluginId = untypedSettings.snapshotPluginId,
+      passivateIdleEntityAfter = untypedSettings.passivateIdleEntityAfter,
       stateStoreMode = StateStoreMode.byName(untypedSettings.stateStoreMode),
       new TuningParameters(untypedSettings.tuningParameters),
       new ClusterSingletonManagerSettings(
@@ -61,6 +61,7 @@ object ClusterShardingSettings {
       journalPluginId = settings.journalPluginId,
       snapshotPluginId = settings.snapshotPluginId,
       stateStoreMode = settings.stateStoreMode.name,
+      passivateIdleEntityAfter = settings.passivateIdleEntityAfter,
       new UntypedShardingSettings.TuningParameters(
         bufferSize = settings.tuningParameters.bufferSize,
         coordinatorFailureBackoff = settings.tuningParameters.coordinatorFailureBackoff,
@@ -233,6 +234,10 @@ object ClusterShardingSettings {
  *   be used for the internal persistence of ClusterSharding. If not defined the default
  *   journal plugin is used. Note that this is not related to persistence used by the entity
  *   actors.
+ * @param passivateIdleEntityAfter Passivate entities that have not received any message in this interval.
+ *   Note that only messages sent through sharding are counted, so direct messages
+ *   to the `ActorRef` of the actor or messages that it sends to itself are not counted as activity.
+ *   Use 0 to disable automatic passivation.
  * @param snapshotPluginId Absolute path to the snapshot plugin configuration entity that is to
  *   be used for the internal persistence of ClusterSharding. If not defined the default
  *   snapshot plugin is used. Note that this is not related to persistence used by the entity
@@ -246,6 +251,7 @@ final class ClusterShardingSettings(
   val rememberEntities:             Boolean,
   val journalPluginId:              String,
   val snapshotPluginId:             String,
+  val passivateIdleEntityAfter:     FiniteDuration,
   val stateStoreMode:               ClusterShardingSettings.StateStoreMode,
   val tuningParameters:             ClusterShardingSettings.TuningParameters,
   val coordinatorSingletonSettings: ClusterSingletonManagerSettings) extends NoSerializationVerificationNeeded {
@@ -290,6 +296,12 @@ final class ClusterShardingSettings(
   def withStateStoreMode(stateStoreMode: ClusterShardingSettings.StateStoreMode): ClusterShardingSettings =
     copy(stateStoreMode = stateStoreMode)
 
+  def withPassivateIdleEntitiesAfter(duration: FiniteDuration): ClusterShardingSettings =
+    copy(passivateIdleEntityAfter = duration)
+
+  def withPassivateIdleEntityAfter(duration: java.time.Duration): ClusterShardingSettings =
+    copy(passivateIdleEntityAfter = duration.asScala)
+
   /**
    * The `role` of the `ClusterSingletonManagerSettings` is not used. The `role` of the
    * coordinator singleton will be the same as the `role` of `ClusterShardingSettings`.
@@ -305,7 +317,8 @@ final class ClusterShardingSettings(
     snapshotPluginId:             String                                   = snapshotPluginId,
     stateStoreMode:               ClusterShardingSettings.StateStoreMode   = stateStoreMode,
     tuningParameters:             ClusterShardingSettings.TuningParameters = tuningParameters,
-    coordinatorSingletonSettings: ClusterSingletonManagerSettings          = coordinatorSingletonSettings): ClusterShardingSettings =
+    coordinatorSingletonSettings: ClusterSingletonManagerSettings          = coordinatorSingletonSettings,
+    passivateIdleEntityAfter:     FiniteDuration                           = passivateIdleEntityAfter): ClusterShardingSettings =
     new ClusterShardingSettings(
       numberOfShards,
       role,
@@ -313,6 +326,7 @@ final class ClusterShardingSettings(
       rememberEntities,
       journalPluginId,
       snapshotPluginId,
+      passivateIdleEntityAfter,
       stateStoreMode,
       tuningParameters,
       coordinatorSingletonSettings)

akka-cluster-sharding/src/main/resources/reference.conf

@@ -23,6 +23,10 @@ akka.cluster.sharding {
   # due to rebalance or crash.
   remember-entities = off
 
+  # Set this to a time duration to have sharding passivate entities when they have not
+  # gotten any message in this long time. Set to 'off' to disable.
+  passivate-idle-entity-after = off
+
   # If the coordinator can't store state changes it will be stopped
   # and started again after this duration, with an exponential back-off
   # of up to 5 times this duration.

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterShardingSettings.scala

@@ -12,6 +12,7 @@ import akka.annotation.InternalApi
 import com.typesafe.config.Config
 import akka.cluster.Cluster
 import akka.cluster.singleton.ClusterSingletonManagerSettings
+import akka.util.JavaDurationConverters._
 
 object ClusterShardingSettings {
 
@@ -53,12 +54,17 @@ object ClusterShardingSettings {
 
     val coordinatorSingletonSettings = ClusterSingletonManagerSettings(config.getConfig("coordinator-singleton"))
 
+    val passivateIdleAfter =
+      if (config.getString("passivate-idle-entity-after").toLowerCase == "off") Duration.Zero
+      else config.getDuration("passivate-idle-entity-after", MILLISECONDS).millis
+
     new ClusterShardingSettings(
       role = roleOption(config.getString("role")),
       rememberEntities = config.getBoolean("remember-entities"),
       journalPluginId = config.getString("journal-plugin-id"),
       snapshotPluginId = config.getString("snapshot-plugin-id"),
       stateStoreMode = config.getString("state-store-mode"),
+      passivateIdleEntityAfter = passivateIdleAfter,
       tuningParameters,
       coordinatorSingletonSettings)
   }
@@ -175,6 +181,7 @@ object ClusterShardingSettings {
         100.milliseconds,
         5)
     }
+
   }
 }
 
@@ -191,6 +198,10 @@ object ClusterShardingSettings {
  *   be used for the internal persistence of ClusterSharding. If not defined the default
  *   snapshot plugin is used. Note that this is not related to persistence used by the entity
  *   actors.
+ * @param passivateIdleEntityAfter Passivate entities that have not received any message in this interval.
+ *   Note that only messages sent through sharding are counted, so direct messages
+ *   to the `ActorRef` of the actor or messages that it sends to itself are not counted as activity.
+ *   Use 0 to disable automatic passivation.
  * @param tuningParameters additional tuning parameters, see descriptions in reference.conf
  */
 final class ClusterShardingSettings(
@@ -199,9 +210,22 @@ final class ClusterShardingSettings(
   val journalPluginId:              String,
   val snapshotPluginId:             String,
   val stateStoreMode:               String,
+  val passivateIdleEntityAfter:     FiniteDuration,
   val tuningParameters:             ClusterShardingSettings.TuningParameters,
   val coordinatorSingletonSettings: ClusterSingletonManagerSettings) extends NoSerializationVerificationNeeded {
 
+  // included for binary compatibility reasons
+  @deprecated("Use the ClusterShardingSettings factory methods or the constructor including passivateIdleEntityAfter instead", "2.5.18")
+  def this(
+    role:                         Option[String],
+    rememberEntities:             Boolean,
+    journalPluginId:              String,
+    snapshotPluginId:             String,
+    stateStoreMode:               String,
+    tuningParameters:             ClusterShardingSettings.TuningParameters,
+    coordinatorSingletonSettings: ClusterSingletonManagerSettings) =
+    this(role, rememberEntities, journalPluginId, snapshotPluginId, stateStoreMode, Duration.Zero, tuningParameters, coordinatorSingletonSettings)
+
   import ClusterShardingSettings.{ StateStoreModePersistence, StateStoreModeDData }
   require(
     stateStoreMode == StateStoreModePersistence || stateStoreMode == StateStoreModeDData,
@@ -231,6 +255,12 @@ final class ClusterShardingSettings(
   def withStateStoreMode(stateStoreMode: String): ClusterShardingSettings =
     copy(stateStoreMode = stateStoreMode)
 
+  def withPassivateIdleAfter(duration: FiniteDuration): ClusterShardingSettings =
+    copy(passivateIdleAfter = duration)
+
+  def withPassivateIdleAfter(duration: java.time.Duration): ClusterShardingSettings =
+    copy(passivateIdleAfter = duration.asScala)
+
   /**
    * The `role` of the `ClusterSingletonManagerSettings` is not used. The `role` of the
    * coordinator singleton will be the same as the `role` of `ClusterShardingSettings`.
@@ -244,14 +274,17 @@ final class ClusterShardingSettings(
     journalPluginId:              String                                   = journalPluginId,
     snapshotPluginId:             String                                   = snapshotPluginId,
     stateStoreMode:               String                                   = stateStoreMode,
+    passivateIdleAfter:           FiniteDuration                           = passivateIdleEntityAfter,
     tuningParameters:             ClusterShardingSettings.TuningParameters = tuningParameters,
     coordinatorSingletonSettings: ClusterSingletonManagerSettings          = coordinatorSingletonSettings): ClusterShardingSettings =
+
     new ClusterShardingSettings(
       role,
       rememberEntities,
       journalPluginId,
       snapshotPluginId,
       stateStoreMode,
+      passivateIdleAfter,
       tuningParameters,
       coordinatorSingletonSettings)
 }

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala

@@ -12,7 +12,6 @@ import akka.actor.ActorSystem
 import akka.actor.Deploy
 import akka.actor.Props
 import akka.actor.Terminated
-import akka.cluster.sharding.Shard.ShardCommand
 import akka.actor.Actor
 import akka.util.MessageBufferMap
 
@@ -26,6 +25,8 @@ import akka.actor.Stash
 import akka.persistence._
 import akka.actor.NoSerializationVerificationNeeded
 
+import scala.concurrent.duration._
+
 /**
  * INTERNAL API
  * @see [[ClusterSharding$ ClusterSharding extension]]
@@ -115,6 +116,9 @@ private[akka] object Shard {
       Props(new Shard(typeName, shardId, entityProps, settings, extractEntityId, extractShardId, handOffStopMessage))
         .withDeploy(Deploy.local)
   }
+
+  private case object PassivateIdleTick extends NoSerializationVerificationNeeded
+
 }
 
 /**
@@ -144,11 +148,20 @@ private[akka] class Shard(
   var state = State.Empty
   var idByRef = Map.empty[ActorRef, EntityId]
   var refById = Map.empty[EntityId, ActorRef]
+  var lastMessageTimestamp = Map.empty[EntityId, Long]
   var passivating = Set.empty[ActorRef]
   val messageBuffers = new MessageBufferMap[EntityId]
 
   var handOffStopper: Option[ActorRef] = None
 
+  import context.dispatcher
+  val passivateIdleTask = if (settings.passivateIdleEntityAfter > Duration.Zero) {
+    val idleInterval = settings.passivateIdleEntityAfter / 2
+    Some(context.system.scheduler.schedule(idleInterval, idleInterval, self, PassivateIdleTick))
+  } else {
+    None
+  }
+
   initialized()
 
   def initialized(): Unit = context.parent ! ShardInitialized(shardId)
@@ -166,6 +179,7 @@ private[akka] class Shard(
     case msg: ShardRegion.StartEntityAck         ⇒ receiveStartEntityAck(msg)
     case msg: ShardRegionCommand                 ⇒ receiveShardRegionCommand(msg)
     case msg: ShardQuery                         ⇒ receiveShardQuery(msg)
+    case PassivateIdleTick                       ⇒ passivateIdleEntities()
     case msg if extractEntityId.isDefinedAt(msg) ⇒ deliverMessage(msg, sender())
   }
 
@@ -176,6 +190,9 @@ private[akka] class Shard(
 
   def receiveStartEntity(start: ShardRegion.StartEntity): Unit = {
     log.debug("Got a request from [{}] to start entity [{}] in shard [{}]", sender(), start.entityId, shardId)
+    if (passivateIdleTask.isDefined) {
+      lastMessageTimestamp = lastMessageTimestamp.updated(start.entityId, System.nanoTime())
+    }
     getEntity(start.entityId)
     sender() ! ShardRegion.StartEntityAck(start.entityId, shardId)
   }
@@ -240,6 +257,9 @@ private[akka] class Shard(
     val id = idByRef(ref)
     idByRef -= ref
     refById -= id
+    if (passivateIdleTask.isDefined) {
+      lastMessageTimestamp -= id
+    }
     if (messageBuffers.getOrEmpty(id).nonEmpty) {
       log.debug("Starting entity [{}] again, there are buffered messages for it", id)
       sendMsgBuffer(EntityStarted(id))
@@ -253,8 +273,6 @@ private[akka] class Shard(
   def passivate(entity: ActorRef, stopMessage: Any): Unit = {
     idByRef.get(entity) match {
       case Some(id) ⇒ if (!messageBuffers.contains(id)) {
-        log.debug("Passivating started on entity {}", id)
-
         passivating = passivating + entity
         messageBuffers.add(id)
         entity ! stopMessage
@@ -265,6 +283,17 @@ private[akka] class Shard(
     }
   }
 
+  def passivateIdleEntities(): Unit = {
+    val deadline = System.nanoTime() - settings.passivateIdleEntityAfter.toNanos
+    val refsToPassivate = lastMessageTimestamp.collect {
+      case (entityId, lastMessageTimestamp) if lastMessageTimestamp < deadline ⇒ refById(entityId)
+    }
+    if (refsToPassivate.nonEmpty) {
+      log.debug("Passivating [{}] idle entities", refsToPassivate.size)
+      refsToPassivate.foreach(passivate(_, handOffStopMessage))
+    }
+  }
+
   // EntityStopped handler
   def passivateCompleted(event: EntityStopped): Unit = {
     log.debug("Entity stopped after passivation [{}]", event.entityId)
@@ -295,25 +324,31 @@ private[akka] class Shard(
     if (id == null || id == "") {
       log.warning("Id must not be empty, dropping message [{}]", msg.getClass.getName)
       context.system.deadLetters ! msg
-    } else if (payload.isInstanceOf[ShardRegion.StartEntity]) {
-      // in case it was wrapped, used in Typed
-      receiveStartEntity(payload.asInstanceOf[ShardRegion.StartEntity])
     } else {
-      messageBuffers.contains(id) match {
-        case false ⇒ deliverTo(id, msg, payload, snd)
+      payload match {
+        case start: ShardRegion.StartEntity ⇒
+          // in case it was wrapped, used in Typed
+          receiveStartEntity(start)
+        case _ ⇒
+          messageBuffers.contains(id) match {
+            case false ⇒ deliverTo(id, msg, payload, snd)
 
-        case true if messageBuffers.totalSize >= bufferSize ⇒
-          log.debug("Buffer is full, dropping message for entity [{}]", id)
-          context.system.deadLetters ! msg
+            case true if messageBuffers.totalSize >= bufferSize ⇒
+              log.debug("Buffer is full, dropping message for entity [{}]", id)
+              context.system.deadLetters ! msg
 
-        case true ⇒
-          log.debug("Message for entity [{}] buffered", id)
-          messageBuffers.append(id, msg, snd)
+            case true ⇒
+              log.debug("Message for entity [{}] buffered", id)
+              messageBuffers.append(id, msg, snd)
+          }
       }
     }
   }
 
   def deliverTo(id: EntityId, msg: Any, payload: Msg, snd: ActorRef): Unit = {
+    if (passivateIdleTask.isDefined) {
+      lastMessageTimestamp = lastMessageTimestamp.updated(id, System.nanoTime())
+    }
     val name = URLEncoder.encode(id, "utf-8")
     context.child(name) match {
       case Some(actor) ⇒ actor.tell(payload, snd)
@@ -329,10 +364,17 @@ private[akka] class Shard(
       val a = context.watch(context.actorOf(entityProps(id), name))
       idByRef = idByRef.updated(a, id)
       refById = refById.updated(id, a)
+      if (passivateIdleTask.isDefined) {
+        lastMessageTimestamp += (id -> System.nanoTime())
+      }
       state = state.copy(state.entities + id)
       a
     }
   }
+
+  override def postStop(): Unit = {
+    passivateIdleTask.foreach(_.cancel())
+  }
 }
 
 private[akka] object RememberEntityStarter {
@@ -425,6 +467,9 @@ private[akka] trait RememberingShard { selfType: Shard ⇒
     val id = idByRef(ref)
     idByRef -= ref
     refById -= id
+    if (passivateIdleTask.isDefined) {
+      lastMessageTimestamp -= id
+    }
     if (messageBuffers.getOrEmpty(id).nonEmpty) {
       //Note; because we're not persisting the EntityStopped, we don't need
       // to persist the EntityStarted either.

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardRegion.scala

@@ -7,7 +7,7 @@ package akka.cluster.sharding
 import java.net.URLEncoder
 
 import akka.pattern.AskTimeoutException
-import akka.util.{ MessageBufferMap, Timeout }
+import akka.util.{ MessageBufferMap, PrettyDuration, Timeout }
 import akka.pattern.{ ask, pipe }
 import akka.actor._
 import akka.cluster.Cluster
@@ -418,6 +418,8 @@ private[akka] class ShardRegion(
   // subscribe to MemberEvent, re-subscribe when restart
   override def preStart(): Unit = {
     cluster.subscribe(self, classOf[MemberEvent])
+    if (settings.passivateIdleEntityAfter > Duration.Zero)
+      log.info("Idle entities will be passivated after [{}]", PrettyDuration.format(settings.passivateIdleEntityAfter))
   }
 
   override def postStop(): Unit = {

akka-cluster-sharding/src/test/scala/akka/cluster/sharding/InactiveEntityPassivationSpec.scala

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package akka.cluster.sharding
+
+import akka.actor.{ Actor, ActorRef, Props }
+import akka.cluster.Cluster
+import akka.cluster.sharding.InactiveEntityPassivationSpec.Entity.GotIt
+import akka.testkit.{ AkkaSpec, TestProbe }
+import com.typesafe.config.ConfigFactory
+
+import scala.concurrent.duration._
+
+object InactiveEntityPassivationSpec {
+  val config = ConfigFactory.parseString("""
+    akka.loglevel = INFO
+    akka.actor.provider = "cluster"
+    akka.remote.netty.tcp.port = 0
+    akka.remote.artery.canonical.port = 0
+    akka.cluster.sharding.passivate-idle-entity-after = 3 s
+    akka.actor.serialize-messages = off
+    """)
+
+  object Passivate
+  object Entity {
+    def props(probe: ActorRef) = Props(new Entity(probe))
+    case class GotIt(id: String, msg: Any, when: Long)
+  }
+  class Entity(probe: ActorRef) extends Actor {
+
+    def id = context.self.path.name
+
+    def receive = {
+      case Passivate ⇒
+        probe ! id + " passivating"
+        context.stop(self)
+      case msg ⇒ probe ! GotIt(id, msg, System.nanoTime())
+    }
+
+  }
+
+  val extractEntityId: ShardRegion.ExtractEntityId = {
+    case msg: Int ⇒ (msg.toString, msg)
+  }
+
+  val extractShardId: ShardRegion.ExtractShardId = {
+    case msg: Int ⇒ (msg % 10).toString
+  }
+
+}
+
+class InactiveEntityPassivationSpec extends AkkaSpec(InactiveEntityPassivationSpec.config) {
+  import InactiveEntityPassivationSpec._
+
+  "Passivation of inactive entities" must {
+
+    "passivate entities when they haven't seen messages for the configured duration" in {
+      // single node cluster
+      Cluster(system).join(Cluster(system).selfAddress)
+      val probe = TestProbe()
+      val settings = ClusterShardingSettings(system)
+      val region = ClusterSharding(system).start(
+        "myType",
+        InactiveEntityPassivationSpec.Entity.props(probe.ref),
+        settings,
+        extractEntityId,
+        extractShardId,
+        ClusterSharding(system).defaultShardAllocationStrategy(settings),
+        Passivate
+      )
+
+      region ! 1
+      region ! 2
+      val responses = Set(
+        probe.expectMsgType[GotIt],
+        probe.expectMsgType[GotIt])
+      responses.map(_.id) should ===(Set("1", "2"))
+      val timeOneSawMessage = responses.find(_.id == "1").get.when
+      Thread.sleep(1000)
+      region ! 2
+      probe.expectMsgType[GotIt].id should ===("2")
+      Thread.sleep(1000)
+      region ! 2
+      probe.expectMsgType[GotIt].id should ===("2")
+
+      // make sure "1" hasn't seen a message in 3 seconds and passivates
+      val timeSinceOneSawAMessage = (System.nanoTime() - timeOneSawMessage).nanos
+      probe.expectNoMessage(3.seconds - timeSinceOneSawAMessage)
+      probe.expectMsg("1 passivating")
+
+      // but it can be re activated just fine:
+      region ! 1
+      region ! 2
+      Set(
+        probe.expectMsgType[GotIt],
+        probe.expectMsgType[GotIt]).map(_.id) should ===(Set("1", "2"))
+
+    }
+  }
+
+}

akka-docs/src/main/paradox/cluster-sharding.md

@@ -334,6 +334,15 @@ then supposed to stop itself. Incoming messages will be buffered by the `Shard`
 between reception of `Passivate` and termination of the entity. Such buffered messages
 are thereafter delivered to a new incarnation of the entity.
 
+### Automatic Passivation
+
+The entities can be configured to be automatically passivated if they haven't received
+a message for a while using the `akka.cluster.sharding.passivate-idle-entity-after` setting,
+or by explicitly setting `ClusterShardingSettings.passivateIdleEntityAfter` to a suitable
+time to keep the actor alive. Note that only messages sent through sharding are counted, so direct messages
+to the `ActorRef` of the actor or messages that it sends to itself are not counted as activity. 
+By default automatic passivation is disabled. 
+
 <a id="cluster-sharding-remembering"></a>
 ## Remembering Entities
 

akka-docs/src/main/paradox/typed/cluster-sharding.md

@@ -116,3 +116,12 @@ Scala
 Java
 :  @@snip [ShardingCompileOnlyTest.java](/akka-cluster-sharding-typed/src/test/java/jdocs/akka/cluster/sharding/typed/ShardingCompileOnlyTest.java) { #counter-messages #counter-passivate #counter-passivate-start }
 
+
+### Automatic Passivation
+
+The entities can be configured to be automatically passivated if they haven't received
+a message for a while using the `akka.cluster.sharding.passivate-idle-entity-after` setting,
+or by explicitly setting `ClusterShardingSettings.passivateIdleEntityAfter` to a suitable
+time to keep the actor alive. Note that only messages sent through sharding are counted, so direct messages
+to the `ActorRef` of the actor or messages that it sends to itself are not counted as activity. 
+By default automatic passivation is disabled.