Leveldb doesn't delete immediately. It will be done by a delayed (sometimes
long) compaction process.
/Patrik
sön 29 nov. 2015 kl. 16:10 skrev Harit Himanshu <
[email protected]>:
> Hello there
>
> This is interesting as I was learning about snapshotting and deleting
> messages in Akka-Persistence. I ran the same class with and without the line
>
> deleteMessages(metadata.sequenceNr - eventDeleteOffset)
>
> in the following code. I am running this with leveldb. The following are
> the results - first without deleting messages and then after deleting
> messages
>
> Harits-MacBook-Pro-2:akka101 harit$ sbt clean
> [info] Loading project definition from
> /Users/harit/IdeaProjects/akka101/project
> [info] Set current project to akka101 (in build
> file:/Users/harit/IdeaProjects/akka101/)
> [success] Total time: 1 s, completed Nov 29, 2015 7:00:30 AM
> Harits-MacBook-Pro-2:akka101 harit$ ls -ltr target/example/snapshots/; ls
> -ltr target/example/journal/
> total 1544
> -rw-r--r-- 1 harit staff 789102 Nov 29 07:01
> snapshot-snapshot-persistence-id-100000-1448809284249
> total 39808
> -rw-r--r-- 1 harit staff 0 Nov 29 07:00 LOCK
> -rw-r--r-- 1 harit staff 16 Nov 29 07:00 CURRENT
> -rw-r--r-- 1 harit staff 3780054 Nov 29 07:01 000005.sst
> -rw-r--r-- 1 harit staff 3782685 Nov 29 07:01 000007.sst
> -rw-r--r-- 1 harit staff 3782685 Nov 29 07:01 000009.sst
> -rw-r--r-- 1 harit staff 3782686 Nov 29 07:01 000011.sst
> -rw-r--r-- 1 harit staff 1048576 Nov 29 07:01 MANIFEST-000002
> -rw-r--r-- 1 harit staff 4194304 Nov 29 07:01 000010.log
>
> Harits-MacBook-Pro-2:akka101 harit$ sbt clean
> [info] Loading project definition from
> /Users/harit/IdeaProjects/akka101/project
> [info] Set current project to akka101 (in build
> file:/Users/harit/IdeaProjects/akka101/)
> [success] Total time: 0 s, completed Nov 29, 2015 7:02:03 AM
>
> Harits-MacBook-Pro-2:akka101 harit$ ls -ltr target/example/snapshots/; ls
> -ltr target/example/journal/
> total 1544
> -rw-r--r-- 1 harit staff 789102 Nov 29 07:02
> snapshot-snapshot-persistence-id-100000-1448809373502
> total 40224
> -rw-r--r-- 1 harit staff 0 Nov 29 07:02 LOCK
> -rw-r--r-- 1 harit staff 16 Nov 29 07:02 CURRENT
> -rw-r--r-- 1 harit staff 3780054 Nov 29 07:02 000005.sst
> -rw-r--r-- 1 harit staff 3782685 Nov 29 07:02 000007.sst
> -rw-r--r-- 1 harit staff 3782685 Nov 29 07:02 000009.sst
> -rw-r--r-- 1 harit staff 3782686 Nov 29 07:02 000011.sst
> -rw-r--r-- 1 harit staff 378 Nov 29 07:03 MANIFEST-000002
> -rw-r--r-- 1 harit staff 5451539 Nov 29 07:03 000010.log
> Harits-MacBook-Pro-2:akka101 harit$
>
>
> To my surprise, I found out that the file sizes are almost similar, even
> after deleting the most of the data
>
> snapshot saved. seqNum:100000, timeStamp:1448809373502
> message deleted till sequenceNumber: 99990
>
> I may be making mistake since I am new to this. I wanted to learn about
>
> - What is that I am doing wrong?
> - What is the best way to test if deleteMessages is actually working
> rather than checking file sizes manually
>
> Thanks everyone.
>
> My complete code is
>
> import akka.actor.{Props, ActorSystem, ActorLogging}
> import akka.event.LoggingReceive
> import akka.persistence._
>
> case class Command(data: String)
>
> case class Event(data: String)
>
> case object InternalState
>
> case object TakeSnapshot
>
> case object ShutDown
>
> case object Fail
>
> case class State(queue: List[String] = Nil) {
> def updated(event: Event): State = copy(event.data :: queue)
>
> def size: Int = queue.length
>
> override def toString: String = queue.reverse.toString
> }
>
> class PersistentSnapshotActor extends PersistentActor with ActorLogging {
> override def persistenceId = "snapshot-persistence-id"
>
> val eventDeleteOffset = 10 // this is to make sure we have some past
> events
> var state = State()
>
> def updateState(event: Event) = state = state.updated(event)
>
> def numberOfEvents = state.size
>
> def receiveRecover = LoggingReceive {
> case event: Event => updateState(event)
> case SnapshotOffer(_, snapshot: State) =>
> println(s"offered state: $snapshot")
> state = snapshot
> }
>
> def receiveCommand = LoggingReceive {
> case Command(data) => persist(Event(data))(updateState)
> case Fail => throw new Exception("killing persistent actor.")
> case ShutDown => context.stop(self)
> case InternalState => println(state)
> case TakeSnapshot => saveSnapshot(state)
> case SaveSnapshotSuccess(metadata) =>
> println(s"snapshot saved. seqNum:${metadata.sequenceNr},
> timeStamp:${metadata.timestamp}")
> deleteMessages(metadata.sequenceNr - eventDeleteOffset)
>
> case SaveSnapshotFailure(_, reason) => println(s"failed to save
> snapshot: $reason")
> case DeleteMessagesSuccess(toSequenceNr) => println(s"message deleted
> till sequenceNumber: $toSequenceNr")
> case DeleteMessagesFailure(reason, toSequenceNr) => println(s"Error in
> deleting message till sequenceNr $toSequenceNr: $reason")
> }
> }
>
> object PersistentSnapshotActorApp extends App {
> val system = ActorSystem("snapshotSystem")
> val persistentActor = system.actorOf(Props[PersistentSnapshotActor],
> "persistentSnapshotActor")
>
> for (i <- 1 to 100000) {
> persistentActor ! Command(i.toString)
> }
> persistentActor ! TakeSnapshot
> persistentActor ! InternalState
> Thread.sleep(60000)
> system.terminate()
> }
>
> My configuration looks like
>
> akka.persistence.journal.plugin = "akka.persistence.journal.leveldb"
> akka.persistence.snapshot-store.plugin =
> "akka.persistence.snapshot-store.local"
>
> akka.persistence.journal.leveldb.dir = "target/example/journal"
> akka.persistence.snapshot-store.local.dir = "target/example/snapshots"
>
> # DO NOT USE THIS IN PRODUCTION !!!
> # See also https://github.com/typesafehub/activator/issues/287
> akka.persistence.journal.leveldb.native = false
>
> --
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