* Replace (deprecate) akka.cluster.auto-down config setting with
akka.cluster.auto-down-unreachable-after
* AutoDown actor that keeps track of unreachable members
and performs down from the leader node when they have been
unreachable for the specified duration
* Migration guide
- introduce around life cycle hooks for symmetry with aroundReceive
- no custom processor-specific life cycle hooks needed any more
- preStart and preRestart can be overridden with empty implementation
(interceptors ensure that super.preXxx calls are still executed)
- all around life cycle hooks can be final
- standard life cycle hooks are non-final to preserve composability with existing traits (FSM, ...)
- use overridden processor and channel ids
- no need anymore to wait for processor instances to stop
- unrelated: fix wrong artifact names in documentation
The most prominent changes compared to eventsourced are:
- No central processor and channel registry any more
- Auto-recovery of processors on start and restart (can be disabled)
- Recovery of processor networks doesn't require coordination
- Explicit channel activation not needed any more
- Message sequence numbers generated per processor (no gaps)
- Sender references are journaled along with messages
- Processors can determine their recovery status
- No custom API on extension object, only messages
- Journal created by extension from config, not by application
- Applications only interact with processors and channels via messages
- Internal design prepared for having processor-specific journal actors (for later optimization possibilities)
Further additions and changes during review:
- Allow processor implementation classes to use inherited stash
- Channel support to resolve (potentially invalid) sender references
- Logical intead of physical deletion of messages
- Pinned dispatcher for LevelDB journal
- Processor can handle failures during recovery
- Message renamed to Persistent
This prototype has the following limitations:
- Serialization of persistent messages and their payload via JavaSerializer only (will be configurable later)
- The LevelDB journal implementation based on a LevelDB Java port, not the native LevelDB (will be configurable later)
The following features will be added later using separate tickets:
- Snapshot-based recovery
- Reliable channels
- Journal plugin API
- Optimizations
- ...
* Replace unreachable Set with Reachability table
* Unreachable members stay in member Set
* Downing a live member was moved it to the unreachable Set,
and then removed from there by the leader. That will not
work when flipping back to reachable, so a Down member must
be detected as unreachable before beeing removed. Similar
to Exiting. Member shuts down itself if it sees itself as
Down.
* Flip back to reachable when failure detector monitors it as
available again
* ReachableMember event
* Can't ignore gossip from aggregated unreachable (see SurviveNetworkInstabilitySpec)
* Make use of ReachableMember event in cluster router
* End heartbeat when acknowledged, EndHeartbeatAck
* Remove nr-of-end-heartbeats from conf
* Full reachability info in JMX cluster status
* Don't use interval after unreachable for AccrualFailureDetector history
* Add QuarantinedEvent to remoting, used for Reachability.Terminated
* Prune reachability table when all reachable
* Update documentation
* Performance testing and optimizations
- add “mailbox-requirement” key to dispatcher section
- split out mailbox section, add akka.actor.default-mailbox
- rewrite findMarker method and use it for Props.create() and getting
the required mailbox of an actor
- add ProducesMessageQueue trait for MailboxType so that requirements
can be checked before trying to create the actor for real
- verify actor as well as dispatcher requirements for message queue
before creation, even in remote-deployed case
- change MessageDispatcher constructor to take a Configurator, add that
to migration guide
Props constructors need to be deprecated instead of being mutated
because we cannot just start throwing exceptions in people’s existing
code. Props.withCreator is deprecated for similar reasons, but also
because Props are about the creators, so replacing that after the fact
is not good style.
