Blocking the sender is a bad for scalability and can even result in deadlocks or starvation if you aren't careful. It's also not location transparent, i.e. it will not work for remote receiver.
If you can't loose messages you should implement a resend-ack protocol for at least once delivery, or make sure that the number of outstanding messages are bounded with some kind of flow control, such as work pulling pattern. It can also be good to consider Akka Streams, since it backpressure is first class in the streams model. Regards, Patrik On Sat, Apr 23, 2016 at 7:50 PM, Shannon Carey <rehevk...@gmail.com> wrote: > I'm a bit confused by the documentation vs. the source code when it comes > to BoundedMailbox and pushTimeOut (aka "mailbox-push-timeout-time"). > > The documentation (http://doc.akka.io/docs/akka/2.4.4/java/mailboxes.html) > says, (implicitly regarding BoundedMailbox), "Other bounded mailbox > implementations which will block the sender if the capacity is reached and > configured with non-zero mailbox-push-timeout-time." > > It also says, (again about BoundedMailbox), "The following mailboxes > should only be used with zero mailbox-push-timeout-time." but it does not > say *why*. > > I found that in Mailboxes#lookupConfigurator(String), there's a warning > when pushTimeOut > zero: > "Configured potentially-blocking mailbox [$id] configured with non-zero > pushTimeOut (${m.pushTimeOut}), which can lead to blocking behaviour when > sending messages to this mailbox. Avoid this by setting > `$id.mailbox-push-timeout-time` to `0`." > > This all implies that if pushTimeOut is zero, that there will be no > blocking and therefore presumably if the mailbox is full the message will > go immediately to dead letters. > > The reason I am confused by this is that BoundedMailbox > uses BoundedMailbox.MessageQueue which is a LinkedBlockingQueue > plus BoundedQueueBasedMessageQueue. If pushTimeOut >= 0, > BoundedQueueBasedMessageQueue defines enqueue() as queue.put() which is > blocking and doesn't send anything to dead letters (contrary to the > documentation). What am I missing? > > What I would like is to guarantee that even if the consuming Actor is slow > that no messages go to dead letters, and instead the producer is blocked > while sending the message. If pushTimeOut=0 with a bounded mailbox is not > the right way to do that, what is? > > Thanks! > Shannon > > -- > >>>>>>>>>> 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 akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > 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 -- >>>>>>>>>> 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 akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
