so, say: Object a = null, Object b = null;
preStart(): a = new something(); a.start(); *<= say I failed here.* b = new somethingElse(); b start(); postStop(): b.stop(); boom NPE. a.stop(); That's why the word transaction exist right? A unit is considered started or valid of all its parts are valid and started... But go ahead, make legacy code life miserable...the decision is yours. Try catch is there for a reason but somehow magic exists. Guido. On Thursday, March 31, 2016 at 1:15:27 PM UTC+1, drewhk wrote: > > > > On Thu, Mar 31, 2016 at 2:10 PM, Guido Medina <[email protected] > <javascript:>> wrote: > >> I haven't seen any system stopping something consciously that it was >> unable to start, the created instance is just an instance like another >> other object which will be GCed. >> > > I don't agree, you might have opened a file or socket in the constructor > or parts of preStart() before the exception. > > >> If you look at it from a state machine perspective Status: CREATED => >> CALL START (or preStart don't worry about details) => Status: Started >> >> It is more destructive to call postStop if it didn't actually started >> because then you will get NPE for stopping things that are part of the >> actor that weren't instantiated. >> > Now I have to protect my code from Akka calling postStop...see my point? >> > > Nope, Akka should just swallow the double-fault at that point. I still > think it should at least attempt to call postStop() to mitigate resource > leaks. > > -Endre > > >> >> Guido. >> >> On Thursday, March 31, 2016 at 9:19:15 AM UTC+1, drewhk wrote: >>> >>> That description suits me ;) >>> >>> On Thu, Mar 31, 2016 at 10:18 AM, Patrik Nordwall <[email protected]> >>> wrote: >>> >>>> From the source: "Only change this if you're very confident and lucky" >>>> :-) >>>> >>>> On Thu, Mar 31, 2016 at 9:30 AM, Endre Varga <[email protected]> >>>> wrote: >>>> >>>>> Shouldn't we all postStop there if preStart has been at least invoked >>>>> (i.e. there is already an instance)? It does not seem to be hard, just >>>>> shuffling that code a bit around (famous last words?). >>>>> >>>>> On Thu, Mar 31, 2016 at 9:25 AM, Patrik Nordwall <[email protected] >>>>> > wrote: >>>>> >>>>>> I think that is how it is implemented. Exception from preStart >>>>>> results in clearing the actor field and >>>>>> throwing ActorInitializationException: >>>>>> >>>>>> https://github.com/akka/akka/blob/master/akka-actor/src/main/scala/akka/actor/ActorCell.scala#L599 >>>>>> >>>>>> Default supervision will result in stop, but postStop is not called >>>>>> because the actor field was cleared: >>>>>> https://github.com/akka/akka/blob/master/akka-actor/src/main/scala/akka/actor/dungeon/FaultHandling.scala#L210 >>>>>> >>>>>> On Wed, Mar 30, 2016 at 10:59 AM, Endre Varga <[email protected] >>>>>> > wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Sun, Mar 27, 2016 at 5:52 PM, Stanislav Savulchik < >>>>>>> [email protected]> wrote: >>>>>>> >>>>>>>> Hi, everyone! >>>>>>>> >>>>>>>> I've discovered that Actor's postStop method doesn't get invoked if >>>>>>>> exception occurs during actor initialization via preStart method. Does >>>>>>>> anyone know if it is the correct behavior? I expected that the failed >>>>>>>> actor >>>>>>>> could close some resources in postStop. >>>>>>>> >>>>>>> >>>>>>> Do you have a reproducer for this? I would also expect postStop to >>>>>>> be at least attempted to be called. >>>>>>> >>>>>>> >>>>>>>> P.S. The behavior differs when a failure occurs during regular vs. >>>>>>>> system message processing and supervisor decides to Stop the failed >>>>>>>> child. >>>>>>>> It seems inconsistent to me. >>>>>>>> >>>>>>> >>>>>>> What do you mean here? Can you provide a small example to show this? >>>>>>> >>>>>>> >>>>>>>> -- >>>>>>>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>>> >>>>>>> >>>>>>> -- >>>>>>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> >>>>>> Patrik Nordwall >>>>>> Akka Tech Lead >>>>>> Lightbend <http://www.lightbend.com/> - Reactive apps on the JVM >>>>>> Twitter: @patriknw >>>>>> >>>>>> [image: Lightbend] <http://www.lightbend.com/> >>>>>> >>>>>> -- >>>>>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- >>>>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> >>>> >>>> -- >>>> >>>> Patrik Nordwall >>>> Akka Tech Lead >>>> Lightbend <http://www.lightbend.com/> - Reactive apps on the JVM >>>> Twitter: @patriknw >>>> >>>> [image: Lightbend] <http://www.lightbend.com/> >>>> >>>> -- >>>> >>>>>>>>>> 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 https://groups.google.com/group/akka-user. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> >>>>>>>>>> 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] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> Visit this group at https://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > -- >>>>>>>>>> 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 https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
