We are close to completing IGNITE-2004 ticket. As part this ticket was made the following changes on public API - if callback has @IgniteAsyncCallback annotation then callback should be run asynchronously - these callbacks are executed in special pool (callback thread pool) which is configured by IgniteConfiguration.asyncCallbackThreadPoolSize
Any comments on this? On Wed, Mar 30, 2016 at 12:45 PM, Yakov Zhdanov <yzhda...@gridgain.com> wrote: > I think this approach works unless user does not initiate number of > concurrent cache operations greater than MSG_QUEUE_SIZE. Where msg queue > size default is 1024, but still configurable. > > Thanks! > -- > Yakov Zhdanov, Director R&D > *GridGain Systems* > www.gridgain.com > > 2016-03-30 11:44 GMT+03:00 Vladimir Ozerov <voze...@gridgain.com>: > > > Does it mean that if cache update rate is greater than filter execution > > rate, then at some point we will stop reading messages from socket? If > yes, > > then it seems we still cannot execute cache operations: > > 1) Filter starts cache operation for a key. Current node is backup for > this > > key. > > 2) Cache message is sent to primary node > > 3) Primary sends message back to current node. > > 4) Message is never read because of backpressure. Cache operation and > > filter never complete. > > > > Am I missing something? > > > > On Wed, Mar 30, 2016 at 11:23 AM, Yakov Zhdanov <yzhda...@apache.org> > > wrote: > > > > > Vladimir, > > > > > > Communication should stop reading from connection is there are too many > > > unprocessed messages. Sender will be blocked on putting message to > queue. > > > > > > --Yakov > > > > > > 2016-03-30 11:11 GMT+03:00 Vladimir Ozerov <voze...@gridgain.com>: > > > > > > > Guys, > > > > > > > > Can you explain how backpressure control is implemented? What if > event > > > > arrival speed is greater than filter processing speed? > > > > > > > > On Wed, Mar 30, 2016 at 10:37 AM, Semyon Boikov < > sboi...@gridgain.com> > > > > wrote: > > > > > > > > > Andrey, > > > > > > > > > > I agree that current situation with threading in Ignite is very > > > > > inconvenient when user callbacks execute some non-trivial code. But > > > > > changing this to async dispatch is huge refactoring, even changing > > this > > > > > just for continuous queries callback is not so easy task. > > > > > > > > > > We can start with > https://issues.apache.org/jira/browse/IGNITE-2004, > > > and > > > > > if > > > > > more users complains arise we can think about changing others parts > > of > > > > > system. > > > > > > > > > > For now we need decisions for these points: > > > > > - how to specify that callback should be run asynchronously > (Nikolay > > > > > suggested marker interface IgniteAsyncCallback, or > > > @IgniteAsyncCallback) > > > > > - where these callbacks are executed, AFAIK Nikolay added special > > pool > > > > > which is configured in IgniteConfiguration (something like > > > > > IgniteConfiguration.asyncCallbackThreadPoolSize) > > > > > > > > > > Regards > > > > > > > > > > > > > > > On Tue, Mar 29, 2016 at 10:45 PM, Andrey Kornev < > > > > andrewkor...@hotmail.com> > > > > > wrote: > > > > > > > > > > > Vladimir, Igniters > > > > > > > > > > > > Here are my 2 cents. > > > > > > > > > > > > The current situation with threading when it comes to executing > > user > > > > > > callbacks -- the CQ filters (either local or remote), the CQ > > > listeners, > > > > > the > > > > > > event listeners, the messaging listeners, the entry processors > > (did I > > > > > miss > > > > > > anything?) -- is pretty sad. The callbacks may get executed on a > > > system > > > > > > pool's thread, public pool's, utility pool's, discovery worker > > > thread, > > > > > > application thread, to name a few. It causes a lot of grief and > > > > > suffering, > > > > > > hard-to-fix races, dead locks and other bugs. > > > > > > > > > > > > I guess it's always possible to come up with a more or less > > > reasonable > > > > > > explanation to such predicament (which usually boils down to "It > is > > > so > > > > > > because this is how it's implemented"), but I, as a user, could > not > > > > care > > > > > > less. I want consistency. I want all my callbacks (including > Entry > > > > > > Processors!) to be executed on the public pool's threads, to be > > > > precise. > > > > > > This is not the first time I complain about this, and I really > > think > > > > it's > > > > > > time to fix this mess. > > > > > > > > > > > > For a good example of how to implement ordered async dispatch of > > > > > callbacks > > > > > > on large scale, one only needs to look at Akka (or Reactor > > > > > > https://github.com/reactor/reactor). Coherence also managed to > > get > > > it > > > > > > right (in my opinion, that is). > > > > > > > > > > > > Regards > > > > > > Andrey > > > > > > > > > > > > > > > > > > > > > > > > > > >
