Hi Patrik,
On Mon, Mar 17, 2014 at 2:22 PM, Patrik Nordwall <[email protected]>wrote: > Hi Ray, > > > On Mon, Mar 17, 2014 at 9:04 AM, Raymond Roestenburg < > [email protected]> wrote: > >> Thanks Martin, but I'm not sure if all my assumptions are correct, and if >> using a child channel is OK in all types of reincarnations. >> >> A couple of questions / assumptions: >> >> - I was expecting that a persistent channel would not redeliver confirmed >> messages (within re-delivery time), and that a reincarnated processor using >> a channel cannot cause re-delivery of confirmed messages because of replay. >> Say I have a processor that responds to a client with a child persistent >> channel, if the client asks and receives the ConfirmablePersistent and >> confirms the message, (taking into account that I'm waiting for the >> Delivered event to occur etc, understanding confirm is async etc), and I >> kill the processor after this confirmation (and implicitly kill channel), >> start a new incarnation (processor with same name), that new processor >> using a new child persistent channel with the same id, the new persistent >> channel should not send old messages to any client that have already been >> confirmed, correct? >> >> What a long sentence, luckily here is a gist that you can look at, I'm >> probably making a rookie mistake :-) I am receiving a message I'm not >> expecting on line 75. Can you explain this? >> >> https://gist.github.com/RayRoestenburg/9595397 >> >> > Yes, that is rather unexpected. I think the reason is that you use the > same channel for delivery of the non-persistent GetNumber reply and the > persistent DecrementAndGet reply. Thereby the sequence numbers becomes > wrong somehow. GetNumber is not replayed. > OK interesting side effect. I did not want the GetNumber to be replayed (since it doesn't effect anything), but I did want clients to receive the response using channel semantics. > > It works if you create two different persistent channels and use one for > GetNumber and one for DecrementAndGet. That can perhaps be improved. Please > open a ticket. > Done. ticket #3933 (https://www.assembla.com/spaces/akka/tickets/3933) > > >> >> - I am expecting that any message I send to a reincarnated processor will >> be received after the replay of that processor. I don't have to deal with >> the fact that replay is asynchronous from a client perspective. So far I've >> seen that this works as expected in my tests, asking just to be sure. >> > > That is correct. They are stashed until the recovery is completed. > > >> >> >> - I first expected that a child _transient_ channel would just work >> across reincarnations, not sending confirmed messages, and later on I >> thought, how can it, since it is killed with the parent processor I'm >> killing. So the new transient child channel (in the new parent) has no way >> to know to ignore confirmed messages once it is created 'again' (better >> said a new channel with the same id), since all of this is in memory. >> Correct? >> > > No, it will de-duplicate in new incarnation also. The Persistent message > in the Deliver message keeps track of the confirmations. > Thanks, the mistake I made was that the channel Id was unstable, I thought it would be stable because I used the same names / paths for the actors in reincarnation, but that alone was not good enough. Using a Channel.props(channelId = ...) made it work in my existing tests. I did think before that the info would be in the journal but started to doubt when I did not get the results in the test. > > >> >> - I _am_ expecting this to work with a persistent child channel, since it >> will use its id to read again from storage and continue where it left off. >> But the above gist shows otherwise? >> > > Channel and PersistentChannel should behave the same in this example, but > it looks like Channel doesn't have the above quirk. > Ok > > >> >> - The confirm() is async, and does not acknowledge back to the confirmer. >> In theory the channel can redeliver the message if the confirmation takes >> too long, there is no way for the channel to check if a confirmation should >> have been received already, and even in a sort of timeout event, it would >> still have to send it again. So in general, even with confirmations, the >> receiver of messages sent from a channel must guard for duplicates (if that >> is a requirement for the application of course). Now in my test the >> redelivery interval is so long it should never happen, but just checking in >> general this assumption is correct. >> > > Yes, that is correct and documented. The confirmation can be lost (or be > delayed) and then a retry is performed and duplicates will arrive, which > must be handled by the destination. > Very clear, great feedback. Thanks Patrik! > /Patrik > > >> >> >> On Mon, Mar 17, 2014 at 7:11 AM, Martin Krasser >> <[email protected]>wrote: >> >>> >>> On 16.03.14 13:14, Raymond Roestenburg wrote: >>> >>> Ok you can also ignore this one, >>> >>> (this is a fantastic rubber ducking session by the way! ;-P) >>> >>> When I create the channel outside of the processor and reuse that, >>> everything works as expected: >>> >>> https://gist.github.com/RayRoestenburg/9582319 >>> >>> Of course every new child channel cannot know which messages were >>> delivered earlier. Duh. >>> >>> >>> You should be able to use a child channel. Just make sure that the >>> channel has the same id across incarnations. It is recommended to pass a >>> channel id via Channel.props (more details at channel >>> identifiers<http://doc.akka.io/docs/akka/2.3.0/scala/persistence.html#id9> >>> ). >>> >>> >>> >>> On Sunday, March 16, 2014 12:42:27 PM UTC+1, Raymond Roestenburg >>> wrote: >>>> >>>> Ok, I've got another question.. I've expanded the gist: >>>> >>>> https://gist.github.com/RayRoestenburg/9581923 >>>> >>>> I've added a channel to respond to clients to the NumberProcessor >>>> example, (NumberProcessorWithChannel) and I see something unexpected again, >>>> which might be me learning how this really works, or a bug? >>>> >>>> When a processor with the same name is started, I see replayed >>>> messages going to the probe which I have previously confirmed. >>>> Is that correct behavior? I would have expected that confirmed messages >>>> are not sent back to clients. >>>> >>>> On Sunday, March 16, 2014 12:01:59 PM UTC+1, Raymond Roestenburg wrote: >>>>> >>>>> Please disregard, I misunderstood and found out why. >>>>> >>>>> The replayed message causes the response back to the probe. >>>>> >>>>> On Sunday, March 16, 2014 10:17:08 AM UTC+1, Raymond Roestenburg >>>>> wrote: >>>>>> >>>>>> Hi guys, >>>>>> >>>>>> I'm writing up some examples for persistence and stumbled on a >>>>>> strange issue. >>>>>> Can you please have a look at this? The gist contains a unit test you >>>>>> can drop straight into akka-persistence to verify it. >>>>>> >>>>>> https://gist.github.com/RayRoestenburg/9580479 >>>>>> >>>>>> I used to use ImplicitSender in the test, and found out that using >>>>>> two probes actually made the test pass, something I think should not be >>>>>> necessary. >>>>>> >>>>>> (There is always the chance that I totally misunderstand or made an >>>>>> incorrect assumption, but I think this is a bug) >>>>>> >>>>>> Cheers, >>>>>> Ray >>>>>> >>>>> -- >>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>> >>>>>>>>>> Check the FAQ: >>> http://doc.akka.io/docs/akka/current/additional/faq.html >>> >>>>>>>>>> Search the archives: >>> https://groups.google.com/group/akka-user >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Akka User List" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/d/optout. >>> >>> >>> -- >>> Martin Krasser >>> >>> blog: http://krasserm.blogspot.com >>> code: http://github.com/krasserm >>> twitter: http://twitter.com/mrt1nz >>> >>> -- >>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>> >>>>>>>>>> Check the FAQ: >>> http://doc.akka.io/docs/akka/current/additional/faq.html >>> >>>>>>>>>> Search the archives: >>> https://groups.google.com/group/akka-user >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Akka User List" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> Raymond Roestenburg >> >> code: http://github.com/RayRoestenburg >> blog: http://roestenburg.agilesquad.com >> twtr: @RayRoestenburg >> book: http://manning.com/roestenburg >> >> -- >> >>>>>>>>>> Read the docs: http://akka.io/docs/ >> >>>>>>>>>> Check the FAQ: >> http://doc.akka.io/docs/akka/current/additional/faq.html >> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user >> --- >> You received this message because you are subscribed to the Google Groups >> "Akka User List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > > Patrik Nordwall > Typesafe <http://typesafe.com/> - Reactive apps on the JVM > Twitter: @patriknw > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Raymond Roestenburg code: http://github.com/RayRoestenburg blog: http://roestenburg.agilesquad.com twtr: @RayRoestenburg book: http://manning.com/roestenburg -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. 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