Hi, I was testing other stuff and change a bunch of code, not related to this but altering the overall message passing sequences, and bingo I get a real exception
[ERROR] [10/02/2015 13:45:46.318] [actor-system-akka.actor.default-dispatcher-6] [akka://actor-system/user/metadata-actor/create-messages/create-PA/liveUIDS] null java.util.ConcurrentModificationException at java.util.ArrayList$SubList.checkForComodification(ArrayList.java:1169) at java.util.ArrayList$SubList.size(ArrayList.java:998) at com.******.*******.***tester.actors.LiveUIDs.populateUIds(LiveUIDs.java:208) line 208 equates to the comment //3 I find this confusing as there is only a single LiveUIds Actor in the runtime. You can see there are 2 message types in the onReceive method and these both later the content of the ArrayList<String> that is 'avail'. MAybe I misunderstand the way messages are processed by an actor. I thought that they were taken off the mailbox quque in the order they arrived? On Friday, 2 October 2015 12:28:38 UTC+1, Akka Team wrote: > > Hi David, > > > > On Thu, Oct 1, 2015 at 10:44 AM, Olddave <[email protected] <javascript:>> > wrote: > >> Hi, >> >> I have a subclass of an UntypedActor that I use a Future to access. It >> works for hundreds of accesses then on the same nth message stalls at the >> same line in a method inside the Actor each time. I get the following stack >> trace, not an exception >> >> >> Thread [actor-system-akka.actor.default-dispatcher-2] (Suspended) >> ActorCell.invoke(Envelope) line: 490 >> Dispatcher$$anon$1(Mailbox).processMailbox(int, long) line: 238 >> Dispatcher$$anon$1(Mailbox).run() line: 220 >> ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec() line: 397 >> ForkJoinExecutorConfigurator$AkkaForkJoinTask(ForkJoinTask<V>).doExec() >> line: 260 >> ForkJoinPool$WorkQueue.runTask(ForkJoinTask<?>) line: 1339 >> ForkJoinExecutorConfigurator$AkkaForkJoinPool(ForkJoinPool).runWorker( >> ForkJoinPool$WorkQueue) line: 1979 >> MonitorableThreadFactory$AkkaForkJoinWorkerThread(ForkJoinWorkerThread). >> run() line: 107 >> >> The relevant parts of the code are >> >> ... >> private HashMap<Integer, List<String>> PA72UIds = new HashMap<Integer, >> List<String>>(); >> ... >> ... >> private UIdUsed getUIds(UIdsRequired msg) { >> UIdUsed result = new UIdUsed(); >> >> >> if (msg.getMpeBuild().getSource() == SOURCE.OMC) { >> result.setuIds24(populateUIds(msg, PA24UIds, 1, OMCLookback)); >> result.setuIds48(populateUIds(msg, PA48UIds, 2, OMCLookback)); >> result.setuIds72(populateUIds(msg, PA72UIds, 3, OMCLookback)); >> //2 >> ... >> ... >> private List<String> populateUIds(UIdsRequired msg, >> HashMap<Integer, List<String>> idHolder, int range, int lookback) { >> >> >> int numReq = msg.getNumRequired(); >> // We split the MPEr across the 5 scan sources equally then in >> // proportion to product duration type >> numReq = numReq/5; >> List<String> avail = null; >> List<String> remaining = null; >> ArrayList<String> availUIds = new ArrayList<String>(0); >> >> >> int i = 0; >> while (availUIds.size() < numReq) { >> // Look one slot closer, after i increments > 0 >> int lookbackSlot = msg.getMpeBuild().getSlot() - lookback + i; >> if (lookbackSlot >= 0) { >> avail = idHolder.get(lookbackSlot); >> if (avail != null && avail.size() >= numReq) { //3 >> ... >> ... >> @Override >> public void onReceive(Object msg) throws Exception { >> if (msg instanceof UIdUsed) { >> addToStore((UIdUsed) msg); >> } else if (msg instanceof UIdsRequired) { >> UIdUsed ids = getUIds((UIdsRequired) msg); //1 >> ... >> >> >> The call count of the Actor is 55 each time when the avail variable >> causes this issue. You can see in the comments I added //1 calls getUIds, >> in getUIds //2 calls populateUIds, the previous 2 calls you see both >> succeed and hit the same line where I later get the error. Then at //3 I >> get the stack trace you see above, it will stall there forever. >> >> I really have no clue how to debug this as there is no exception, it just >> stops there and the timeout on the Future that sent the message triggers. >> > > This looks weird, but from this I cannot really see what the issue. What > is clear that something very wrong happens in internal message processing. > Is there something among your calls that can cause an InterrputedException? > Are you using blocking calls? Are you using a non-default mailbox? > > Does anything in that code using assert? > > -Endre > > >> >> Can someone explain how you debug this type of issue? >> >> Thx >> >> David >> >> -- >> >>>>>>>>>> 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 http://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Akka Team > Typesafe - Reactive apps on the JVM > Blog: letitcrash.com > Twitter: @akkateam > -- >>>>>>>>>> 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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