Configuration
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Configuration

You can start using Akka without defining any configuration, since sensible default values are provided. Later on you might need to amend the settings to change the default behavior or adapt for specific runtime environments. Typical examples of settings that you might amend:

  • log level and logger backend
  • enable remoting
  • message serializers
  • definition of routers
  • tuning of dispatchers

Akka uses the Typesafe Config Library, which might also be a good choice for the configuration of your own application or library built with or without Akka. This library is implemented in Java with no external dependencies; you should have a look at its documentation (in particular about ConfigFactory), which is only summarized in the following.

Warning

If you use Akka from the Scala REPL from the 2.9.x series, and you do not provide your own ClassLoader to the ActorSystem, start the REPL with "-Yrepl-sync" to work around a deficiency in the REPLs provided Context ClassLoader.

Where configuration is read from

All configuration for Akka is held within instances of ActorSystem, or put differently, as viewed from the outside, ActorSystem is the only consumer of configuration information. While constructing an actor system, you can either pass in a Config object or not, where the second case is equivalent to passing ConfigFactory.load() (with the right class loader). This means roughly that the default is to parse all application.conf, application.json and application.properties found at the root of the class path—please refer to the aforementioned documentation for details. The actor system then merges in all reference.conf resources found at the root of the class path to form the fallback configuration, i.e. it internally uses

appConfig.withFallback(ConfigFactory.defaultReference(classLoader))

The philosophy is that code never contains default values, but instead relies upon their presence in the reference.conf supplied with the library in question.

Highest precedence is given to overrides given as system properties, see the HOCON specification (near the bottom). Also noteworthy is that the application configuration—which defaults to application—may be overridden using the config.resource property (there are more, please refer to the Config docs).

Note

If you are writing an Akka application, keep you configuration in application.conf at the root of the class path. If you are writing an Akka-based library, keep its configuration in reference.conf at the root of the JAR file.

When using JarJar, OneJar, Assembly or any jar-bundler

Warning

Akka's configuration approach relies heavily on the notion of every module/jar having its own reference.conf file, all of these will be discovered by the configuration and loaded. Unfortunately this also means that if you put/merge multiple jars into the same jar, you need to merge all the reference.confs as well. Otherwise all defaults will be lost and Akka will not function.

Custom application.conf

A custom application.conf might look like this:

# In this file you can override any option defined in the reference files.
# Copy in parts of the reference files and modify as you please.

akka {

  # Loggers to register at boot time (akka.event.Logging$DefaultLogger logs
  # to STDOUT)
  loggers = ["akka.event.slf4j.Slf4jLogger"]

  # Log level used by the configured loggers (see "loggers") as soon
  # as they have been started; before that, see "stdout-loglevel"
  # Options: OFF, ERROR, WARNING, INFO, DEBUG
  loglevel = "DEBUG"

  # Log level for the very basic logger activated during AkkaApplication startup
  # Options: OFF, ERROR, WARNING, INFO, DEBUG
  stdout-loglevel = "DEBUG"

  actor {
    default-dispatcher {
      # Throughput for default Dispatcher, set to 1 for as fair as possible
      throughput = 10
    }
  }

  remote {
    server {
      # The port clients should connect to. Default is 2552 (AKKA)
      port = 2562
    }
  }
}

Including files

Sometimes it can be useful to include another configuration file, for example if you have one application.conf with all environment independent settings and then override some settings for specific environments.

Specifying system property with -Dconfig.resource=/dev.conf will load the dev.conf file, which includes the application.conf

dev.conf:

include "application"

akka {
  loglevel = "DEBUG"
}

More advanced include and substitution mechanisms are explained in the HOCON specification.

Logging of Configuration

If the system or config property akka.log-config-on-start is set to on, then the complete configuration at INFO level when the actor system is started. This is useful when you are uncertain of what configuration is used.

If in doubt, you can also easily and nicely inspect configuration objects before or after using them to construct an actor system:

Welcome to Scala version 2.10.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_27).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import com.typesafe.config._
import com.typesafe.config._

scala> ConfigFactory.parseString("a.b=12")
res0: com.typesafe.config.Config = Config(SimpleConfigObject({"a" : {"b" : 12}}))

scala> res0.root.render
res1: java.lang.String =
{
    # String: 1
    "a" : {
        # String: 1
        "b" : 12
    }
}

The comments preceding every item give detailed information about the origin of the setting (file & line number) plus possible comments which were present, e.g. in the reference configuration. The settings as merged with the reference and parsed by the actor system can be displayed like this:

final ActorSystem system = ActorSystem.create();
println(system.settings());
// this is a shortcut for system.settings().config().root().render()

A Word About ClassLoaders

In several places of the configuration file it is possible to specify the fully-qualified class name of something to be instantiated by Akka. This is done using Java reflection, which in turn uses a ClassLoader. Getting the right one in challenging environments like application containers or OSGi bundles is not always trivial, the current approach of Akka is that each ActorSystem implementation stores the current thread’s context class loader (if available, otherwise just its own loader as in this.getClass.getClassLoader) and uses that for all reflective accesses. This implies that putting Akka on the boot class path will yield NullPointerException from strange places: this is simply not supported.

Application specific settings

The configuration can also be used for application specific settings. A good practice is to place those settings in an Extension, as described in:

Configuring multiple ActorSystem

If you have more than one ActorSystem (or you're writing a library and have an ActorSystem that may be separate from the application's) you may want to separate the configuration for each system.

Given that ConfigFactory.load() merges all resources with matching name from the whole class path, it is easiest to utilize that functionality and differentiate actor systems within the hierarchy of the configuration:

myapp1 {
  akka.loglevel = "WARNING"
  my.own.setting = 43
}
myapp2 {
  akka.loglevel = "ERROR"
  app2.setting = "appname"
}
my.own.setting = 42
my.other.setting = "hello"
val config = ConfigFactory.load()
val app1 = ActorSystem("MyApp1", config.getConfig("myapp1").withFallback(config))
val app2 = ActorSystem("MyApp2",
  config.getConfig("myapp2").withOnlyPath("akka").withFallback(config))

These two samples demonstrate different variations of the “lift-a-subtree” trick: in the first case, the configuration accessible from within the actor system is this

akka.loglevel = "WARNING"
my.own.setting = 43
my.other.setting = "hello"
// plus myapp1 and myapp2 subtrees

while in the second one, only the “akka” subtree is lifted, with the following result

akka.loglevel = "ERROR"
my.own.setting = 42
my.other.setting = "hello"
// plus myapp1 and myapp2 subtrees

Note

The configuration library is really powerful, explaining all features exceeds the scope affordable here. In particular not covered are how to include other configuration files within other files (see a small example at Including files) and copying parts of the configuration tree by way of path substitutions.

You may also specify and parse the configuration programmatically in other ways when instantiating the ActorSystem.

import akka.actor.ActorSystem
import com.typesafe.config.ConfigFactory
    val customConf = ConfigFactory.parseString("""
      akka.actor.deployment {
        /my-service {
          router = round-robin
          nr-of-instances = 3
        }
      }
      """)
    // ConfigFactory.load sandwiches customConfig between default reference
    // config and default overrides, and then resolves it.
    val system = ActorSystem("MySystem", ConfigFactory.load(customConf))

Reading configuration from a custom location

You can replace or supplement application.conf either in code or using system properties.

If you're using ConfigFactory.load() (which Akka does by default) you can replace application.conf by defining -Dconfig.resource=whatever, -Dconfig.file=whatever, or -Dconfig.url=whatever.

From inside your replacement file specified with -Dconfig.resource and friends, you can include "application" if you still want to use application.{conf,json,properties} as well. Settings specified before include "application" would be overridden by the included file, while those after would override the included file.

In code, there are many customization options.

There are several overloads of ConfigFactory.load(); these allow you to specify something to be sandwiched between system properties (which override) and the defaults (from reference.conf), replacing the usual application.{conf,json,properties} and replacing -Dconfig.file and friends.

The simplest variant of ConfigFactory.load() takes a resource basename (instead of application); myname.conf, myname.json, and myname.properties would then be used instead of application.{conf,json,properties}.

The most flexible variant takes a Config object, which you can load using any method in ConfigFactory. For example you could put a config string in code using ConfigFactory.parseString() or you could make a map and ConfigFactory.parseMap(), or you could load a file.

You can also combine your custom config with the usual config, that might look like:

// make a Config with just your special setting
Config myConfig =
  ConfigFactory.parseString("something=somethingElse");
// load the normal config stack (system props,
// then application.conf, then reference.conf)
Config regularConfig =
  ConfigFactory.load();
// override regular stack with myConfig
Config combined =
  myConfig.withFallback(regularConfig);
// put the result in between the overrides
// (system props) and defaults again
Config complete =
  ConfigFactory.load(combined);
// create ActorSystem
ActorSystem system =
  ActorSystem.create("myname", complete);

When working with Config objects, keep in mind that there are three "layers" in the cake:

  • ConfigFactory.defaultOverrides() (system properties)
  • the app's settings
  • ConfigFactory.defaultReference() (reference.conf)

The normal goal is to customize the middle layer while leaving the other two alone.

  • ConfigFactory.load() loads the whole stack
  • the overloads of ConfigFactory.load() let you specify a different middle layer
  • the ConfigFactory.parse() variations load single files or resources

To stack two layers, use override.withFallback(fallback); try to keep system props (defaultOverrides()) on top and reference.conf (defaultReference()) on the bottom.

Do keep in mind, you can often just add another include statement in application.conf rather than writing code. Includes at the top of application.conf will be overridden by the rest of application.conf, while those at the bottom will override the earlier stuff.

Listing of the Reference Configuration

Each Akka module has a reference configuration file with the default values.

akka-actor

####################################
# Akka Actor Reference Config File #
####################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

akka {
  # Akka version, checked against the runtime version of Akka.
  version = "2.2-M3"

  # Home directory of Akka, modules in the deploy directory will be loaded
  home = ""

  # Loggers to register at boot time (akka.event.Logging$DefaultLogger logs
  # to STDOUT)
  loggers = ["akka.event.Logging$DefaultLogger"]

  # Deprecated, use akka.loggers.
  event-handlers = []

  # Loggers are created and registered synchronously during ActorSystem
  # start-up, and since they are actors, this timeout is used to bound the
  # waiting time
  logger-startup-timeout = 5s

  # Deprecated, use akka.loggers-startup-timeout
  event-handler-startup-timeout = -1s

  # Log level used by the configured loggers (see "loggers") as soon
  # as they have been started; before that, see "stdout-loglevel"
  # Options: OFF, ERROR, WARNING, INFO, DEBUG
  loglevel = "INFO"

  # Log level for the very basic logger activated during AkkaApplication startup
  # Options: OFF, ERROR, WARNING, INFO, DEBUG
  stdout-loglevel = "WARNING"

  # Log the complete configuration at INFO level when the actor system is started.
  # This is useful when you are uncertain of what configuration is used.
  log-config-on-start = off

  # List FQCN of extensions which shall be loaded at actor system startup.
  # Should be on the format: 'extensions = ["foo", "bar"]' etc.
  # See the Akka Documentation for more info about Extensions
  extensions = []

  # Toggles whether threads created by this ActorSystem should be daemons or not
  daemonic = off

  # JVM shutdown, System.exit(-1), in case of a fatal error,
  # such as OutOfMemoryError
  jvm-exit-on-fatal-error = on

  actor {

    # FQCN of the ActorRefProvider to be used; the below is the built-in default,
    # another one is akka.remote.RemoteActorRefProvider in the akka-remote bundle.
    provider = "akka.actor.LocalActorRefProvider"

    # The guardian "/user" will use this class to obtain its supervisorStrategy.
    # It needs to be a subclass of akka.actor.SupervisorStrategyConfigurator.
    # In addition to the default there is akka.actor.StoppingSupervisorStrategy.
    guardian-supervisor-strategy = "akka.actor.DefaultSupervisorStrategy"

    # Timeout for ActorSystem.actorOf
    creation-timeout = 20s

    # Frequency with which stopping actors are prodded in case they had to be
    # removed from their parents
    reaper-interval = 5s

    # Serializes and deserializes (non-primitive) messages to ensure immutability,
    # this is only intended for testing.
    serialize-messages = off

    # Serializes and deserializes creators (in Props) to ensure that they can be
    # sent over the network, this is only intended for testing.
    serialize-creators = off

    # Timeout for send operations to top-level actors which are in the process
    # of being started. This is only relevant if using a bounded mailbox or the
    # CallingThreadDispatcher for a top-level actor.
    unstarted-push-timeout = 10s

    typed {
      # Default timeout for typed actor methods with non-void return type
      timeout = 5s
    }

    deployment {

      # deployment id pattern - on the format: /parent/child etc.
      default {

        # The id of the dispatcher to use for this actor.
        # If undefined or empty the dispatcher specified in code
        # (Props.withDispatcher) is used, or default-dispatcher if not
        # specified at all.
        dispatcher = ""

        # The id of the mailbox to use for this actor.
        # If undefined or empty the default mailbox of the configured dispatcher
        # is used or if there is no mailbox configuration the mailbox specified
        # in code (Props.withMailbox) is used.
        # If there is a mailbox defined in the configured dispatcher then that
        # overrides this setting.
        mailbox = ""

        # routing (load-balance) scheme to use
        # - available: "from-code", "round-robin", "random", "smallest-mailbox",
        #              "scatter-gather", "broadcast"
        # - or:        Fully qualified class name of the router class.
        #              The class must extend akka.routing.CustomRouterConfig and
        #              have a public constructor with com.typesafe.config.Config
        #              parameter.
        # - default is "from-code";
        # Whether or not an actor is transformed to a Router is decided in code
        # only (Props.withRouter). The type of router can be overridden in the
        # configuration; specifying "from-code" means that the values specified
        # in the code shall be used.
        # In case of routing, the actors to be routed to can be specified
        # in several ways:
        # - nr-of-instances: will create that many children
        # - routees.paths: will look the paths up using actorFor and route to
        #   them, i.e. will not create children
        # - resizer: dynamically resizable number of routees as specified in
        #   resizer below
        router = "from-code"

        # number of children to create in case of a router;
        # this setting is ignored if routees.paths is given
        nr-of-instances = 1

        # within is the timeout used for routers containing future calls
        within = 5 seconds

        # number of virtual nodes per node for consistent-hashing router
        virtual-nodes-factor = 10

        routees {
          # Alternatively to giving nr-of-instances you can specify the full
          # paths of those actors which should be routed to. This setting takes
          # precedence over nr-of-instances
          paths = []
        }

        # Routers with dynamically resizable number of routees; this feature is
        # enabled by including (parts of) this section in the deployment
        resizer {

          # The fewest number of routees the router should ever have.
          lower-bound = 1

          # The most number of routees the router should ever have.
          # Must be greater than or equal to lower-bound.
          upper-bound = 10

          # Threshold used to evaluate if a routee is considered to be busy
          # (under pressure). Implementation depends on this value (default is 1).
          # 0:   number of routees currently processing a message.
          # 1:   number of routees currently processing a message has
          #      some messages in mailbox.
          # > 1: number of routees with at least the configured pressure-threshold
          #      messages in their mailbox. Note that estimating mailbox size of
          #      default UnboundedMailbox is O(N) operation.
          pressure-threshold = 1

          # Percentage to increase capacity whenever all routees are busy.
          # For example, 0.2 would increase 20% (rounded up), i.e. if current
          # capacity is 6 it will request an increase of 2 more routees.
          rampup-rate = 0.2

          # Minimum fraction of busy routees before backing off.
          # For example, if this is 0.3, then we'll remove some routees only when
          # less than 30% of routees are busy, i.e. if current capacity is 10 and
          # 3 are busy then the capacity is unchanged, but if 2 or less are busy
          # the capacity is decreased.
          # Use 0.0 or negative to avoid removal of routees.
          backoff-threshold = 0.3

          # Fraction of routees to be removed when the resizer reaches the
          # backoffThreshold.
          # For example, 0.1 would decrease 10% (rounded up), i.e. if current
          # capacity is 9 it will request an decrease of 1 routee.
          backoff-rate = 0.1

          # When the resizer reduce the capacity the abandoned routee actors are
          # stopped with PoisonPill after this delay. The reason for the delay is
          # to give concurrent messages a chance to be placed in mailbox before
          # sending PoisonPill.
          # Use 0s to skip delay.
          stop-delay = 1s

          # Number of messages between resize operation.
          # Use 1 to resize before each message.
          messages-per-resize = 10
        }
      }
    }

    default-dispatcher {
      # Must be one of the following
      # Dispatcher, (BalancingDispatcher, only valid when all actors using it are
      # of the same type), PinnedDispatcher, or a FQCN to a class inheriting
      # MessageDispatcherConfigurator with a public constructor with
      # both com.typesafe.config.Config parameter and
      # akka.dispatch.DispatcherPrerequisites parameters.
      # PinnedDispatcher must be used toghether with executor=thread-pool-executor.
      type = "Dispatcher"

      # Which kind of ExecutorService to use for this dispatcher
      # Valid options:
      #  - "fork-join-executor" requires a "fork-join-executor" section
      #  - "thread-pool-executor" requires a "thread-pool-executor" section
      #  - A FQCN of a class extending ExecutorServiceConfigurator
      executor = "fork-join-executor"

      # This will be used if you have set "executor = "fork-join-executor""
      fork-join-executor {
        # Min number of threads to cap factor-based parallelism number to
        parallelism-min = 8

        # The parallelism factor is used to determine thread pool size using the
        # following formula: ceil(available processors * factor). Resulting size
        # is then bounded by the parallelism-min and parallelism-max values.
        parallelism-factor = 3.0

        # Max number of threads to cap factor-based parallelism number to
        parallelism-max = 64
      }

      # This will be used if you have set "executor = "thread-pool-executor""
      thread-pool-executor {
        # Keep alive time for threads
        keep-alive-time = 60s

        # Min number of threads to cap factor-based core number to
        core-pool-size-min = 8

        # The core pool size factor is used to determine thread pool core size
        # using the following formula: ceil(available processors * factor).
        # Resulting size is then bounded by the core-pool-size-min and
        # core-pool-size-max values.
        core-pool-size-factor = 3.0

        # Max number of threads to cap factor-based number to
        core-pool-size-max = 64

        # Minimum number of threads to cap factor-based max number to
        # (if using a bounded task queue)
        max-pool-size-min = 8

        # Max no of threads (if using a bounded task queue) is determined by
        # calculating: ceil(available processors * factor)
        max-pool-size-factor  = 3.0

        # Max number of threads to cap factor-based max number to
        # (if using a  bounded task queue)
        max-pool-size-max = 64

        # Specifies the bounded capacity of the task queue (< 1 == unbounded)
        task-queue-size = -1

        # Specifies which type of task queue will be used, can be "array" or
        # "linked" (default)
        task-queue-type = "linked"

        # Allow core threads to time out
        allow-core-timeout = on
      }

      # How long time the dispatcher will wait for new actors until it shuts down
      shutdown-timeout = 1s

      # Throughput defines the number of messages that are processed in a batch
      # before the thread is returned to the pool. Set to 1 for as fair as possible.
      throughput = 5

      # Throughput deadline for Dispatcher, set to 0 or negative for no deadline
      throughput-deadline-time = 0ms

      # If negative (or zero) then an unbounded mailbox is used (default)
      # If positive then a bounded mailbox is used and the capacity is set using
      # the property
      # NOTE: setting a mailbox to 'blocking' can be a bit dangerous, could lead
      # to deadlock, use with care
      # The following mailbox-push-timeout-time is only used for type=Dispatcher
      # and only if mailbox-capacity > 0
      mailbox-capacity = -1

      # Specifies the timeout to add a new message to a mailbox that is full -
      # negative number means infinite timeout. It is only used for type=Dispatcher
      # and only if mailbox-capacity > 0
      mailbox-push-timeout-time = 10s

      # FQCN of the MailboxType, if not specified the default bounded or unbounded
      # mailbox is used. The Class of the FQCN must have a public constructor with
      # (akka.actor.ActorSystem.Settings, com.typesafe.config.Config) parameters.
      mailbox-type = ""

      # For BalancingDispatcher: If the balancing dispatcher should attempt to
      # schedule idle actors using the same dispatcher when a message comes in,
      # and the dispatchers ExecutorService is not fully busy already.
      attempt-teamwork = on

      # For Actor with Stash: The default capacity of the stash.
      # If negative (or zero) then an unbounded stash is used (default)
      # If positive then a bounded stash is used and the capacity is set using
      # the property
      stash-capacity = -1
    }

    mailbox {
      # Mapping between message queue semantics and mailbox configurations.
      # Used by akka.dispatch.RequiresMessageQueue[T] to enforce different
      # mailbox types on actors.
      # If your Actor implements RequiresMessageQueue[T], then when you create
      # an instance of that actor its mailbox type will be decided by looking
      # up a mailbox configuration via T in this mapping
      requirements {
        "akka.dispatch.DequeBasedMessageQueue" = akka.actor.mailbox.unbounded-deque-based
      }

      unbounded-deque-based {
        # FQCN of the MailboxType, The Class of the FQCN must have a public constructor
        # with (akka.actor.ActorSystem.Settings, com.typesafe.config.Config) parameters.
        mailbox-type = "akka.dispatch.UnboundedDequeBasedMailbox"
      }
    }

    debug {
      # enable function of Actor.loggable(), which is to log any received message
      # at DEBUG level, see the “Testing Actor Systems” section of the Akka
      # Documentation at http://akka.io/docs
      receive = off

      # enable DEBUG logging of all AutoReceiveMessages (Kill, PoisonPill et.c.)
      autoreceive = off

      # enable DEBUG logging of actor lifecycle changes
      lifecycle = off

      # enable DEBUG logging of all LoggingFSMs for events, transitions and timers
      fsm = off

      # enable DEBUG logging of subscription changes on the eventStream
      event-stream = off

      # enable DEBUG logging of unhandled messages
      unhandled = off

      # enable WARN logging of misconfigured routers
      router-misconfiguration = off
    }

    # Entries for pluggable serializers and their bindings.
    serializers {
      java = "akka.serialization.JavaSerializer"
      bytes = "akka.serialization.ByteArraySerializer"
    }

    # Class to Serializer binding. You only need to specify the name of an
    # interface or abstract base class of the messages. In case of ambiguity it
    # is using the most specific configured class, or giving a warning and
    # choosing the “first” one.
    #
    # To disable one of the default serializers, assign its class to "none", like
    # "java.io.Serializable" = none
    serialization-bindings {
      "[B" = bytes
      "java.io.Serializable" = java
    }

    # Configuration items which are used by the akka.actor.ActorDSL._ methods
    dsl {
      # Maximum queue size of the actor created by newInbox(); this protects
      # against faulty programs which use select() and consistently miss messages
      inbox-size = 1000

      # Default timeout to assume for operations like Inbox.receive et al
      default-timeout = 5s
    }
  }

  # Used to set the behavior of the scheduler.
  # Changing the default values may change the system behavior drastically so make
  # sure you know what you're doing! See the Scheduler section of the Akka
  # Documentation for more details.
  scheduler {
    # The HashedWheelTimer (HWT) implementation from Netty is used as the default
    # scheduler in the system.
    # HWT does not execute the scheduled tasks on exact time.
    # It will, on every tick, check if there are any tasks behind the schedule
    # and execute them. You can increase or decrease the accuracy of the execution
    # timing by specifying smaller or larger tick duration.
    # If you are scheduling a lot of tasks you should consider increasing the
    # ticks per wheel.
    # For more information see: http://www.jboss.org/netty/
    # Note that it might take up to 1 tick to stop the Timer, so setting the
    # tick-duration to a high value will make shutting down the actor system
    # take longer.
    tick-duration = 100ms

    # The timer uses a circular wheel of buckets to store the timer tasks.
    # This should be set such that the majority of scheduled timeouts (for high
    # scheduling frequency) will be shorter than one rotation of the wheel
    # (ticks-per-wheel * ticks-duration)
    # THIS MUST BE A POWER OF TWO!
    ticks-per-wheel = 512

    # This setting selects the timer implementation which shall be loaded at
    # system start-up. Built-in choices are:
    #  - akka.actor.LightArrayRevolverScheduler
    #  - akka.actor.DefaultScheduler (HWT) DEPRECATED
    # (to be benchmarked and evaluated)
    # The class given here must implement the akka.actor.Scheduler interface
    # and offer a public constructor which takes three arguments:
    #  1) com.typesafe.config.Config
    #  2) akka.event.LoggingAdapter
    #  3) java.util.concurrent.ThreadFactory
    implementation = akka.actor.LightArrayRevolverScheduler

    # When shutting down the scheduler, there will typically be a thread which
    # needs to be stopped, and this timeout determines how long to wait for
    # that to happen. In case of timeout the shutdown of the actor system will
    # proceed without running possibly still enqueued tasks.
    shutdown-timeout = 5s
  }

  io {

    # By default the select loops run on dedicated threads, hence using a
    # PinnedDispatcher
    pinned-dispatcher {
      type = "PinnedDispatcher"
      executor = "thread-pool-executor"
      thread-pool-executor.allow-core-pool-timeout = off
    }

    tcp {

      # The number of selectors to stripe the served channels over; each of
      # these will use one select loop on the selector-dispatcher.
      nr-of-selectors = 1

      # Maximum number of open channels supported by this TCP module; there is
      # no intrinsic general limit, this setting is meant to enable DoS
      # protection by limiting the number of concurrently connected clients.
      # Also note that this is a "soft" limit; in certain cases the implementation
      # will accept a few connections more or a few less than the number configured
      # here. Must be an integer > 0 or "unlimited".
      max-channels = 256000

      # The select loop can be used in two modes:
      # - setting "infinite" will select without a timeout, hogging a thread
      # - setting a positive timeout will do a bounded select call,
      #   enabling sharing of a single thread between multiple selectors
      #   (in this case you will have to use a different configuration for the
      #   selector-dispatcher, e.g. using "type=Dispatcher" with size 1)
      # - setting it to zero means polling, i.e. calling selectNow()
      select-timeout = infinite

      # When trying to assign a new connection to a selector and the chosen
      # selector is at full capacity, retry selector choosing and assignment
      # this many times before giving up
      selector-association-retries = 10

      # The maximum number of connection that are accepted in one go,
      # higher numbers decrease latency, lower numbers increase fairness on
      # the worker-dispatcher
      batch-accept-limit = 10

      # The number of bytes per direct buffer in the pool used to read or write
      # network data from the kernel.
      direct-buffer-size = 128 KiB

      # The maximal number of direct buffers kept in the direct buffer pool for
      # reuse.
      direct-buffer-pool-limit = 1000

      # The duration a connection actor waits for a `Register` message from
      # its commander before aborting the connection.
      register-timeout = 5s

      # The maximum number of bytes delivered by a `Received` message. Before
      # more data is read from the network the connection actor will try to
      # do other work.
      max-received-message-size = unlimited

      # Enable fine grained logging of what goes on inside the implementation.
      # Be aware that this may log more than once per message sent to the actors
      # of the tcp implementation.
      trace-logging = off

      # Fully qualified config path which holds the dispatcher configuration
      # to be used for running the select() calls in the selectors
      selector-dispatcher = "akka.io.pinned-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the read/write worker actors
      worker-dispatcher = "akka.actor.default-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the selector management actors
      management-dispatcher = "akka.actor.default-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # on which file IO tasks are scheduled
      file-io-dispatcher = "akka.actor.default-dispatcher"

      # The maximum number of bytes (or "unlimited") to transfer in one batch when using
      # `WriteFile` command which uses `FileChannel.transferTo` to pipe files to a TCP socket.
      # On some OS like Linux `FileChannel.transferTo` may block for a long time when network
      # IO is faster than file IO. Decreasing the value may improve fairness while increasing
      # may improve throughput.
      file-io-transferTo-limit = 512 KiB
    }

    udp {

      # The number of selectors to stripe the served channels over; each of
      # these will use one select loop on the selector-dispatcher.
      nr-of-selectors = 1

      # Maximum number of open channels supported by this UDP module Generally
      # UDP does not require a large number of channels, therefore it is
      # recommended to keep this setting low.
      max-channels = 4096

      # The select loop can be used in two modes:
      # - setting "infinite" will select without a timeout, hogging a thread
      # - setting a positive timeout will do a bounded select call,
      #   enabling sharing of a single thread between multiple selectors
      #   (in this case you will have to use a different configuration for the
      #   selector-dispatcher, e.g. using "type=Dispatcher" with size 1)
      # - setting it to zero means polling, i.e. calling selectNow()
      select-timeout = infinite

      # When trying to assign a new connection to a selector and the chosen
      # selector is at full capacity, retry selector choosing and assignment
      # this many times before giving up
      selector-association-retries = 10

      # The maximum number of datagrams that are read in one go,
      # higher numbers decrease latency, lower numbers increase fairness on
      # the worker-dispatcher
      receive-throughput = 3

      # The number of bytes per direct buffer in the pool used to read or write
      # network data from the kernel.
      direct-buffer-size = 128 KiB

      # The maximal number of direct buffers kept in the direct buffer pool for
      # reuse.
      direct-buffer-pool-limit = 1000

      # The maximum number of bytes delivered by a `Received` message. Before
      # more data is read from the network the connection actor will try to
      # do other work.
      received-message-size-limit = unlimited

      # Enable fine grained logging of what goes on inside the implementation.
      # Be aware that this may log more than once per message sent to the actors
      # of the tcp implementation.
      trace-logging = off

      # Fully qualified config path which holds the dispatcher configuration
      # to be used for running the select() calls in the selectors
      selector-dispatcher = "akka.io.pinned-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the read/write worker actors
      worker-dispatcher = "akka.actor.default-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the selector management actors
      management-dispatcher = "akka.actor.default-dispatcher"
    }

    udp-connected {

      # The number of selectors to stripe the served channels over; each of
      # these will use one select loop on the selector-dispatcher.
      nr-of-selectors = 1

      # Maximum number of open channels supported by this UDP module Generally
      # UDP does not require a large number of channels, therefore it is
      # recommended to keep this setting low.
      max-channels = 4096

      # The select loop can be used in two modes:
      # - setting "infinite" will select without a timeout, hogging a thread
      # - setting a positive timeout will do a bounded select call,
      #   enabling sharing of a single thread between multiple selectors
      #   (in this case you will have to use a different configuration for the
      #   selector-dispatcher, e.g. using "type=Dispatcher" with size 1)
      # - setting it to zero means polling, i.e. calling selectNow()
      select-timeout = infinite

      # When trying to assign a new connection to a selector and the chosen
      # selector is at full capacity, retry selector choosing and assignment
      # this many times before giving up
      selector-association-retries = 10

      # The maximum number of datagrams that are read in one go,
      # higher numbers decrease latency, lower numbers increase fairness on
      # the worker-dispatcher
      receive-throughput = 3

      # The number of bytes per direct buffer in the pool used to read or write
      # network data from the kernel.
      direct-buffer-size = 128 KiB

      # The maximal number of direct buffers kept in the direct buffer pool for
      # reuse.
      direct-buffer-pool-limit = 1000

      # The maximum number of bytes delivered by a `Received` message. Before
      # more data is read from the network the connection actor will try to
      # do other work.
      received-message-size-limit = unlimited

      # Enable fine grained logging of what goes on inside the implementation.
      # Be aware that this may log more than once per message sent to the actors
      # of the tcp implementation.
      trace-logging = off

      # Fully qualified config path which holds the dispatcher configuration
      # to be used for running the select() calls in the selectors
      selector-dispatcher = "akka.io.pinned-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the read/write worker actors
      worker-dispatcher = "akka.actor.default-dispatcher"

      # Fully qualified config path which holds the dispatcher configuration
      # for the selector management actors
      management-dispatcher = "akka.actor.default-dispatcher"
    }


    # IMPORTANT NOTICE:
    #
    # The following settings belong to the deprecated akka.actor.IO
    # implementation and will be removed once that is removed. They are not
    # taken into account by the akka.io.* implementation, which is configured
    # above!

    # In bytes, the size of the shared read buffer. In the span 0b..2GiB.
    #
    read-buffer-size = 8KiB

    # Specifies how many ops are done between every descriptor selection
    select-interval = 100

    # Number of connections that are allowed in the backlog.
    # 0 or negative means that the platform default will be used.
    default-backlog = 1000
  }


}

akka-remote

#####################################
# Akka Remote Reference Config File #
#####################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

# comments about akka.actor settings left out where they are already in akka-
# actor.jar, because otherwise they would be repeated in config rendering.

akka {

  actor {

    serializers {
      proto = "akka.remote.serialization.ProtobufSerializer"
      daemon-create = "akka.remote.serialization.DaemonMsgCreateSerializer"
    }


    serialization-bindings {
      # Since com.google.protobuf.Message does not extend Serializable but
      # GeneratedMessage does, need to use the more specific one here in order
      # to avoid ambiguity
      "com.google.protobuf.GeneratedMessage" = proto
      "akka.remote.DaemonMsgCreate" = daemon-create
    }

    deployment {

      default {

        # if this is set to a valid remote address, the named actor will be
        # deployed at that node e.g. "akka://sys@host:port"
        remote = ""

        target {

          # A list of hostnames and ports for instantiating the children of a
          # router
          #   The format should be on "akka://sys@host:port", where:
          #    - sys is the remote actor system name
          #    - hostname can be either hostname or IP address the remote actor
          #      should connect to
          #    - port should be the port for the remote server on the other node
          # The number of actor instances to be spawned is still taken from the
          # nr-of-instances setting as for local routers; the instances will be
          # distributed round-robin among the given nodes.
          nodes = []

        }
      }
    }
  }

  remote {

    ### General settings

    # Timeout after which the startup of the remoting subsystem is considered
    # to be failed. Increase this value if your transport drivers (see the
    # enabled-transports section) need longer time to be loaded.
    startup-timeout = 10 s

    # Timout after which the graceful shutdown of the remoting subsystem is
    # considered to be failed. After the timeout the remoting system is
    # forcefully shut down. Increase this value if your transport drivers
    # (see the enabled-transports section) need longer time to stop properly.
    shutdown-timeout = 10 s

    # Before shutting down the drivers, the remoting subsystem attempts to flush
    # all pending writes. This setting controls the maximum time the remoting is
    # willing to wait before moving on to shut down the drivers.
    flush-wait-on-shutdown = 2 s

    # Reuse inbound connections for outbound messages
    use-passive-connections = on

    # Dispatcher that the actors responsible to write to a connection will use.
    # The mailbox type must be always a DequeBasedMailbox.
    writer-dispatcher {
      mailbox-type = "akka.dispatch.UnboundedDequeBasedMailbox"
    }

    # Controls the backoff interval after a refused write is reattempted. (Transports may
    # refuse writes if their internal buffer is full)
    backoff-interval = 0.01 s

    # Acknowledgment timeout of management commands sent to the transport stack.
    command-ack-timeout = 30 s

    ### Security settings

    # Enable untrusted mode for full security of server managed actors, prevents
    # system messages to be send by clients, e.g. messages like 'Create',
    # 'Suspend', 'Resume', 'Terminate', 'Supervise', 'Link' etc.
    untrusted-mode = off

    # Should the remote server require that its peers share the same
    # secure-cookie (defined in the 'remote' section)? Secure cookies are passed
    # between during the initial handshake. Connections are refused if the initial
    # message contains a mismatching cookie or the cookie is missing.
    require-cookie = off

    # Generate your own with the script availbale in
    # '$AKKA_HOME/scripts/generate_config_with_secure_cookie.sh' or using
    # 'akka.util.Crypt.generateSecureCookie'
    secure-cookie = ""

    ### Logging

    # If this is "on", Akka will log all inbound messages at DEBUG level,
    # if off then they are not logged
    log-received-messages = off

    # If this is "on", Akka will log all outbound messages at DEBUG level,
    # if off then they are not logged
    log-sent-messages = off

    # If this is "on", Akka will log all RemoteLifeCycleEvents at the level
    # defined for each, if off then they are not logged. Failures to deserialize
    # received messages also fall under this flag.
    log-remote-lifecycle-events = on

    ### Failure detection and recovery

    # Settings for the Phi accrual failure detector (http://ddg.jaist.ac.jp/pub/HDY+04.pdf
    # [Hayashibara et al]) used by the remoting subsystem to detect failed connections.
    transport-failure-detector {

      # FQCN of the failure detector implementation.
      # It must implement akka.remote.FailureDetector and have
      # a public constructor with a com.typesafe.config.Config parameter.
      implementation-class = "akka.remote.PhiAccrualFailureDetector"

      # How often keep-alive heartbeat messages should be sent to each connection.
      heartbeat-interval = 1 s

      # Defines the failure detector threshold.
      # A low threshold is prone to generate many wrong suspicions but ensures
      # a quick detection in the event of a real crash. Conversely, a high
      # threshold generates fewer mistakes but needs more time to detect
      # actual crashes.
      threshold = 7.0

      # Number of the samples of inter-heartbeat arrival times to adaptively
      # calculate the failure timeout for connections.
      max-sample-size = 100

      # Minimum standard deviation to use for the normal distribution in
      # AccrualFailureDetector. Too low standard deviation might result in
      # too much sensitivity for sudden, but normal, deviations in heartbeat
      # inter arrival times.
      min-std-deviation = 100 ms

      # Number of potentially lost/delayed heartbeats that will be
      # accepted before considering it to be an anomaly.
      # This margin is important to be able to survive sudden, occasional,
      # pauses in heartbeat arrivals, due to for example garbage collect or
      # network drop.
      acceptable-heartbeat-pause = 3 s
    }

    # Settings for the Phi accrual failure detector (http://ddg.jaist.ac.jp/pub/HDY+04.pdf
    # [Hayashibara et al]) used for remote death watch.
    watch-failure-detector {

      # FQCN of the failure detector implementation.
      # It must implement akka.remote.FailureDetector and have
      # a public constructor with a com.typesafe.config.Config parameter.
      implementation-class = "akka.remote.PhiAccrualFailureDetector"

      # How often keep-alive heartbeat messages should be sent to each connection.
      heartbeat-interval = 1 s

      # Defines the failure detector threshold.
      # A low threshold is prone to generate many wrong suspicions but ensures
      # a quick detection in the event of a real crash. Conversely, a high
      # threshold generates fewer mistakes but needs more time to detect
      # actual crashes.
      threshold = 10.0

      # Number of the samples of inter-heartbeat arrival times to adaptively
      # calculate the failure timeout for connections.
      max-sample-size = 200

      # Minimum standard deviation to use for the normal distribution in
      # AccrualFailureDetector. Too low standard deviation might result in
      # too much sensitivity for sudden, but normal, deviations in heartbeat
      # inter arrival times.
      min-std-deviation = 100 ms

      # Number of potentially lost/delayed heartbeats that will be
      # accepted before considering it to be an anomaly.
      # This margin is important to be able to survive sudden, occasional,
      # pauses in heartbeat arrivals, due to for example garbage collect or
      # network drop.
      acceptable-heartbeat-pause = 4 s


      # How often to check for nodes marked as unreachable by the failure
      # detector
      unreachable-nodes-reaper-interval = 1s

      # After the heartbeat request has been sent the first failure detection
      # will start after this period, even though no heartbeat mesage has
      # been received.
      expected-response-after = 3 s

      # When a node unwatch another node it will end that
      # with this number of EndHeartbeatRequest messages, which will stop the
      # heartbeating from the other side
      nr-of-end-heartbeats = 8

    }

    # After failed to establish an outbound connection, the remoting will mark the
    # address as failed. This configuration option controls how much time should
    # be elapsed before reattempting a new connection. While the address is
    # gated, all messages sent to the address are delivered to dead-letters.
    # If this setting is 0, the remoting will always immediately reattempt
    # to establish a failed outbound connection and will buffer writes until
    # it succeeds.
    retry-gate-closed-for = 0 s

    # If the retry gate function is disabled (see retry-gate-closed-for) the
    # remoting subsystem will always attempt to reestablish failed outbound
    # connections. The settings below together control the maximum number of
    # reattempts in a given time window. The number of reattempts during
    # a window of "retry-window" will be maximum "maximum-retries-in-window".
    retry-window = 3 s
    maximum-retries-in-window = 5

    # The length of time to gate an address whose name lookup has failed.
    # No connection attempts will be made to an address while it remains
    # gated. Any messages sent to a gated address will be directed to dead
    # letters instead. Name lookups are costly, and the time to recovery
    # is typically large, therefore this setting should be a value in the
    # order of seconds or minutes.
    gate-unknown-addresses-for = 60 s

    # This settings controls how long a system will be quarantined after
    # catastrophic communication failures that result in the loss of system
    # messages. Quarantining prevents communication with the remote system
    # of a given UID. This function can be disabled by setting the value
    # to "off".
    quarantine-systems-for = 60s

    # This setting defines the maximum number of unacknowledged system messages
    # allowed for a remote system. If this limit is reached the remote system is
    # declared to be dead and its UID marked as tainted.
    system-message-buffer-size = 1000

    # This setting defines the maximum idle time after an individual
    # acknowledgement for system messages is sent. System message delivery
    # is guaranteed by explicit acknowledgement messages. These acks are
    # piggybacked on ordinary traffic messages. If no traffic is detected
    # during the time period configured here, the remoting will send out
    # an individual ack.
    system-message-ack-piggyback-timeout = 0.3 s

    # This setting defines the time after messages that have not been
    # explicitly acknowledged or negatively acknowledged are resent.
    # Messages that were negatively acknowledged are always immediately
    # resent.
    resend-interval = 1 s

    ### Transports and adapters

    # List of the transport drivers that will be loaded by the remoting.
    # A list of fully qualified config paths must be provided where
    # the given configuration path contains a transport-class key
    # pointing to an implementation class of the Transport interface.
    # If multiple transports are provided, the address of the first
    # one will be used as a default address.
    enabled-transports = ["akka.remote.netty.tcp"]

    # Transport drivers can be augmented with adapters by adding their
    # name to the applied-adapters setting in the configuration of a
    # transport. The available adapters should be configured in this
    # section by providing a name, and the fully qualified name of
    # their corresponding implementation. The class given here
    # must implement akka.akka.remote.transport.TransportAdapterProvider
    # and have public constructor without parameters.
    adapters {
      gremlin = "akka.remote.transport.FailureInjectorProvider"
      trttl = "akka.remote.transport.ThrottlerProvider"
    }

    ### Default configuration for the Netty based transport drivers

    netty.tcp {
      # The class given here must implement the akka.remote.transport.Transport
      # interface and offer a public constructor which takes two arguments:
      #  1) akka.actor.ExtendedActorSystem
      #  2) com.typesafe.config.Config
      transport-class = "akka.remote.transport.netty.NettyTransport"

      # Transport drivers can be augmented with adapters by adding their
      # name to the applied-adapters list. The last adapter in the
      # list is the adapter immediately above the driver, while
      # the first one is the top of the stack below the standard
      # Akka protocol
      applied-adapters = []

      transport-protocol = tcp

      # The default remote server port clients should connect to.
      # Default is 2552 (AKKA), use 0 if you want a random available port
      # This port needs to be unique for each actor system on the same machine.
      port = 2552

      # The hostname or ip to bind the remoting to,
      # InetAddress.getLocalHost.getHostAddress is used if empty
      hostname = ""

      # Enables SSL support on this transport
      enable-ssl = false

      # Sets the connectTimeoutMillis of all outbound connections,
      # i.e. how long a connect may take until it is timed out
      connection-timeout = 120s

      # If set to "<id.of.dispatcher>" then the specified dispatcher
      # will be used to accept inbound connections, and perform IO. If "" then
      # dedicated threads will be used.
      use-dispatcher-for-io = ""

      # Sets the high water mark for the in and outbound sockets,
      # set to 0b for platform default
      write-buffer-high-water-mark = 0b

      # Sets the low water mark for the in and outbound sockets,
      # set to 0b for platform default
      write-buffer-low-water-mark = 0b

      # Sets the send buffer size of the Sockets,
      # set to 0b for platform default
      send-buffer-size = 32000b

      # Sets the receive buffer size of the Sockets,
      # set to 0b for platform default
      receive-buffer-size = 32000b

      # Sets the size of the connection backlog
      backlog = 4096

      # Used to configure the number of I/O worker threads on server sockets
      server-socket-worker-pool {
        # Min number of threads to cap factor-based number to
        pool-size-min = 2

        # The pool size factor is used to determine thread pool size
        # using the following formula: ceil(available processors * factor).
        # Resulting size is then bounded by the pool-size-min and
        # pool-size-max values.
        pool-size-factor = 1.0

        # Max number of threads to cap factor-based number to
        pool-size-max = 8
      }

      # Used to configure the number of I/O worker threads on client sockets
      client-socket-worker-pool {
        # Min number of threads to cap factor-based number to
        pool-size-min = 2

        # The pool size factor is used to determine thread pool size
        # using the following formula: ceil(available processors * factor).
        # Resulting size is then bounded by the pool-size-min and
        # pool-size-max values.
        pool-size-factor = 1.0

        # Max number of threads to cap factor-based number to
        pool-size-max = 8
      }


    }

    netty.udp = ${akka.remote.netty.tcp}
    netty.udp {
      transport-protocol = udp
    }

    netty.ssl = ${akka.remote.netty.tcp}
    netty.ssl = {
      # Enable SSL/TLS encryption.
      # This must be enabled on both the client and server to work.
      enable-ssl = true

      security {
        # This is the Java Key Store used by the server connection
        key-store = "keystore"

        # This password is used for decrypting the key store
        key-store-password = "changeme"

        # This password is used for decrypting the key
        key-password = "changeme"

        # This is the Java Key Store used by the client connection
        trust-store = "truststore"

        # This password is used for decrypting the trust store
        trust-store-password = "changeme"

        # Protocol to use for SSL encryption, choose from:
        # Java 6 & 7:
        #   'SSLv3', 'TLSv1'
        # Java 7:
        #   'TLSv1.1', 'TLSv1.2'
        protocol = "TLSv1"

        # Example: ["TLS_RSA_WITH_AES_128_CBC_SHA", "TLS_RSA_WITH_AES_256_CBC_SHA"]
        # You need to install the JCE Unlimited Strength Jurisdiction Policy
        # Files to use AES 256.
        # More info here:
        # http://docs.oracle.com/javase/7/docs/technotes/guides/security/SunProviders.html#SunJCEProvider
        enabled-algorithms = ["TLS_RSA_WITH_AES_128_CBC_SHA"]

        # There are three options, in increasing order of security:
        # "" or SecureRandom => (default)
        # "SHA1PRNG" => Can be slow because of blocking issues on Linux
        # "AES128CounterSecureRNG" => fastest startup and based on AES encryption
        # algorithm
        # "AES256CounterSecureRNG"
        # The following use one of 3 possible seed sources, depending on
        # availability: /dev/random, random.org and SecureRandom (provided by Java)
        # "AES128CounterInetRNG"
        # "AES256CounterInetRNG" (Install JCE Unlimited Strength Jurisdiction
        # Policy Files first)
        # Setting a value here may require you to supply the appropriate cipher
        # suite (see enabled-algorithms section above)
        random-number-generator = ""
      }
    }

  }

}

akka-testkit

######################################
# Akka Testkit Reference Config File #
######################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

akka {
  test {
    # factor by which to scale timeouts during tests, e.g. to account for shared
    # build system load
    timefactor =  1.0

    # duration of EventFilter.intercept waits after the block is finished until
    # all required messages are received
    filter-leeway = 3s

    # duration to wait in expectMsg and friends outside of within() block
    # by default
    single-expect-default = 3s

    # The timeout that is added as an implicit by DefaultTimeout trait
    default-timeout = 5s

    calling-thread-dispatcher {
      type = akka.testkit.CallingThreadDispatcherConfigurator
    }
  }
}

akka-transactor

#########################################
# Akka Transactor Reference Config File #
#########################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

akka {
  transactor {
    # The timeout used for coordinated transactions across actors
    coordinated-timeout = 5s
  }
}

akka-agent

####################################
# Akka Agent Reference Config File #
####################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

akka {
  agent {

    # The dispatcher used for agent-send-off actor
    send-off-dispatcher {
      executor = thread-pool-executor
      type = PinnedDispatcher
    }

    # The dispatcher used for agent-alter-off actor
    alter-off-dispatcher {
      executor = thread-pool-executor
      type = PinnedDispatcher
    }
  }
}

akka-zeromq

#####################################
# Akka ZeroMQ Reference Config File #
#####################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

akka {

  zeromq {

    # The default timeout for a poll on the actual zeromq socket.
    poll-timeout = 100ms

    # Timeout for creating a new socket
    new-socket-timeout = 5s

    socket-dispatcher {
      # A zeromq socket needs to be pinned to the thread that created it.
      # Changing this value results in weird errors and race conditions within
      # zeromq
      executor = thread-pool-executor
      type = "PinnedDispatcher"
      thread-pool-executor.allow-core-timeout = off
    }
  }
}

akka-file-mailbox

#############################################
# Akka File Mailboxes Reference Config File #
#############################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.
#
# For more information see <https://github.com/robey/kestrel/>

akka {
  actor {
    mailbox {
      file-based {
        # directory below which this queue resides
        directory-path = "./_mb"

        # attempting to add an item after the queue reaches this size (in items)
        # will fail.
        max-items = 2147483647

        # attempting to add an item after the queue reaches this size (in bytes)
        # will fail.
        max-size = 2147483647 bytes

        # attempting to add an item larger than this size (in bytes) will fail.
        max-item-size = 2147483647 bytes

        # maximum expiration time for this queue (seconds).
        max-age = 0s

        # maximum journal size before the journal should be rotated.
        max-journal-size = 16 MiB

        # maximum size of a queue before it drops into read-behind mode.
        max-memory-size = 128 MiB

        # maximum overflow (multiplier) of a journal file before we re-create it.
        max-journal-overflow = 10

        # absolute maximum size of a journal file until we rebuild it,
        # no matter what.
        max-journal-size-absolute = 9223372036854775807 bytes

        # whether to drop older items (instead of newer) when the queue is full
        discard-old-when-full = on

        # whether to keep a journal file at all
        keep-journal = on

        # whether to sync the journal after each transaction
        sync-journal = off

        # circuit breaker configuration
        circuit-breaker {
          # maximum number of failures before opening breaker
          max-failures = 3

          # duration of time beyond which a call is assumed to be timed out and
          # considered a failure
          call-timeout = 3 seconds

          # duration of time to wait until attempting to reset the breaker during
          # which all calls fail-fast
          reset-timeout = 30 seconds
        }
      }
    }
  }
}

Contents