Re: [infinispan-dev] New algorithm to handle remote commands

Thanks Pedro, this looks great. However, I don't think it's ok to treat CommitCommands/Pessimistic PrepareCommands as RemoteLockCommands just because they may send L1 invalidation commands. It's true that those commands will block, but there's no need to wait for any other command before doing the L1 invalidation. In fact, the non-tx writes on backup owners, which you consider to be non-blocking, can also send L1 invalidation commands (see L1NonTxInterceptor.invalidateL1). On the other hand, one of the good things that the remote executor did was to allow queueing lots of commands with a higher topology id, when one of the nodes receives the new topology much later than the others. We still have to consider each TopologyAffectedCommand as potentially blocking and put it through the remote executor. And InvalidateL1Commands are also TopologyAffectedCommands, so there's still a potential for deadlock when L1 is enabled and we have maxThreads write commands blocked sending L1 invalidations and those L1 invalidation commands are stuck in the remote executor's queue on another node. And with (very) unlucky timing the remote executor might not even get to create maxThreads threads before the deadlock appears. I wonder if we could write a custom executor that checks what the first task in the queue is every second or so, and creates a bunch of new threads if the first task in the queue hasn't changed. You're right about the remote executor getting full as well, we're lacking any feedback mechanism to tell the sender to slow down, except for blocking the OOB thread.

I wonder if we could tell JGroups somehow to discard the message from inside MessageDispatcher.handle (e.g. throw a DiscardMessageException), so the sender has to retransmit it

and we don't block the OOB thread. That should allow us to set a size limit on the BlockingTaskAwareExecutor's blockedTasks collection as well. Bela, WDYT? Cheers Dan On Wed, Sep 17, 2014 at 7:17 PM, Pedro Ruivo <pedro(a)infinispan.org <mailto:pedro@infinispan.org>> wrote: new link: https://github.com/infinispan/infinispan/wiki/Remote-Command-Handler On 09/17/2014 05:08 PM, Pedro Ruivo wrote: > Hi, > > I've just wrote on the wiki a new algorithm to better handle the remote > commands. You can find it in [1]. > > If you have questions, suggestion or just want to discuss some aspect, > please do in thread. I'll update the wiki page based on this discussion > > Thanks. > > Cheers, > Pedro > > [1]https://github.com/infinispan/infinispan/wiki/Remote-Command-Handler-(W....) > _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org <mailto:infinispan-dev@lists.jboss.org> https://lists.jboss.org/mailman/listinfo/infinispan-dev _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev