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 > >
