Val, Sounds like a great solution. I'm totally for it.
-- Denis On Thu, Apr 5, 2018 at 12:32 PM, Valentin Kulichenko < valentin.kuliche...@gmail.com> wrote: > Denis, > > This is why I'm suggesting to use DeploymentSpi for this. The way I see > this is that instead of deploying classes on local classpath, user can > deploy them in the storage that SPI points to. If class is updated in the > storage, Ignite detects this and automatically restarts the service. This > is a very simple and straightforward approach that doesn't required a lot > of changes on our side and allows to reuse existing implementation of > DeploymentSpi. > > -Val > > On Thu, Apr 5, 2018 at 12:13 PM, Denis Magda <dma...@gridgain.com> wrote: > > > > > > > There is no need to deserialize services on the coordinator. It should > > only > > > be able to calculate the assignments. > > > *LazyServiceConfiguration *should be used to deliver the service > > > configurations, just like it is done right now. > > > > > > Can that configuration be tweaked over the time requiring to update the > > class on all the nodes (if, for instance, someone wants to deploy the > next > > version of a service)? Just want to be sure we don't need to restart the > > cluster nodes (that won't be used for service deployments) on > > services-related configurational changes. > > > > -- > > Denis > > > > On Thu, Apr 5, 2018 at 8:18 AM, Denis Mekhanikov <dmekhani...@gmail.com> > > wrote: > > > > > Denis, > > > There is no need to deserialize services on the coordinator. It should > > only > > > be able to calculate the assignments. > > > *LazyServiceConfiguration *should be used to deliver the service > > > configurations, just like it is done right now. > > > > > > Val, > > > Usage of DeploymentSpi is a good idea, I didn't think about this > > > possibility. > > > This is a viable alternative to peer-class-loading, not that > > user-friendly > > > though. > > > But if peer-class-loading is that hard to implement, then I vote for > > > DeploymentSpi. > > > As far as I understand, it won't require us to do any additional > changes > > in > > > Ignite, but will make users think about using a proper DeploymentSpi. > > > Please correct me, if I'm wrong. > > > It would be good, though, to add some examples on service redeployment, > > > when implementation class changes. > > > > > > Denis > > > > > > чт, 5 апр. 2018 г. в 2:33, Valentin Kulichenko < > > > valentin.kuliche...@gmail.com>: > > > > > > > I don't think peer class loading is even possible for services. I > > believe > > > > we should reuse DeploymentSpi [1] for versioning. > > > > > > > > [1] https://apacheignite.readme.io/docs/deployment-spi > > > > > > > > -Val > > > > > > > > On Wed, Apr 4, 2018 at 12:52 PM, Denis Magda <dma...@gridgain.com> > > > wrote: > > > > > > > > > Sorry, that was me who renamed the IEP to "Oil Change in Service > > Grid". > > > > Was > > > > > writing this email after the renaming. Like that title more because > > > it's > > > > > fun and highlights what we're intended to do - cleaning of our > > service > > > > grid > > > > > engine and powering it up with new "liquid" (new communication and > > > > > deployment approach not available before). > > > > > > > > > > Denis > > > > > > > > > > > > > > > > This message contains serialized service instance and its > > > > configuration. > > > > > > It is delivered to the coordinator node first, that calculates > the > > > > > service > > > > > > deployment assignments and adds this information to the message. > > > > > > > > > > > > > > > I would consider using a NodeFilter first to decide where a service > > can > > > > be > > > > > potentially deployed. Otherwise, we would require service classes > to > > > be > > > > on > > > > > every node (every node might become a coordinator) which is not the > > > > desired > > > > > requirement. > > > > > > > > > > > > > > > As for the peer-class-loading, I would backup up Dmitriy here. > Let's > > at > > > > > least not to focus on this task for now. We should design services > > > > > versioning in the right way first and support it. > > > > > > > > > > -- > > > > > Denis > > > > > > > > > > > > > > > > > > > > On Wed, Apr 4, 2018 at 12:20 PM, Dmitriy Setrakyan < > > > > dsetrak...@apache.org> > > > > > wrote: > > > > > > > > > > > Here is the correct link: > > > > > > https://cwiki.apache.org/confluence/display/IGNITE/IEP- > > > > > > 17%3A+Oil+Change+in+Service+Grid > > > > > > > > > > > > I have looked at the tickets there, and I believe that we should > > not > > > > > > support peer-deployment for services. It is very hard and I do > not > > > > think > > > > > we > > > > > > should even try. > > > > > > > > > > > > I am proposing closing this ticket as Won't Fix - > > > > > > https://issues.apache.org/jira/browse/IGNITE-975 > > > > > > > > > > > > D. > > > > > > > > > > > > On Wed, Apr 4, 2018 at 5:39 AM, Denis Mekhanikov < > > > > dmekhani...@gmail.com> > > > > > > wrote: > > > > > > > > > > > > > Vyacheslav, > > > > > > > > > > > > > > I've just posted my first draft of the IEP: > > > > > > > https://cwiki.apache.org/confluence/display/IGNITE/IEP- > > > > > > 17%3A+Service+grid+ > > > > > > > improvements > > > > > > > It's not finished yet, but you can get the idea from it. > > > > > > > If you have some thoughts on your mind, please let me know, > I'll > > > add > > > > > them > > > > > > > to the IEP. > > > > > > > > > > > > > > Denis > > > > > > > > > > > > > > ср, 4 апр. 2018 г. в 13:09, Vyacheslav Daradur < > > > daradu...@gmail.com > > > > >: > > > > > > > > > > > > > > > Denis, thanks for the link. > > > > > > > > > > > > > > > > I looked through the task and I think that understand your > > > redesign > > > > > > point > > > > > > > > now. > > > > > > > > > > > > > > > > Do you have a clear plan or IEP for the whole redesign? > > > > > > > > > > > > > > > > I'm interested in this component and I'd like to take part in > > the > > > > > > > > development. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > On Mon, Apr 2, 2018 at 2:55 PM, Denis Mekhanikov < > > > > > > dmekhani...@gmail.com> > > > > > > > > wrote: > > > > > > > > > Vyacheslav, > > > > > > > > > > > > > > > > > > Service deployment design, based on replicated utility > cache > > > has > > > > > > proven > > > > > > > > to > > > > > > > > > be unstable and deadlock-prone. > > > > > > > > > You can find a list of JIRA issues, connected to it, in my > > > > previous > > > > > > > > letter. > > > > > > > > > > > > > > > > > > The intention behind it is similar to the binary metadata > > > > redesign, > > > > > > > that > > > > > > > > > happened in the following ticket: IGNITE-4157 > > > > > > > > > <https://issues.apache.org/jira/browse/IGNITE-4157> > > > > > > > > > This change in service deployment procedure will eliminate > > need > > > > for > > > > > > > > another > > > > > > > > > internal replicated cache > > > > > > > > > and make service deployment more reliable on unstable > > topology. > > > > > > > > > > > > > > > > > > Denis > > > > > > > > > > > > > > > > > > вт, 27 мар. 2018 г. в 23:21, Vyacheslav Daradur < > > > > > daradu...@gmail.com > > > > > > >: > > > > > > > > > > > > > > > > > >> Hi, Denis Mekhanikov! > > > > > > > > >> > > > > > > > > >> As far as I know, Ignite services are based on IgniteCache > > and > > > > we > > > > > > have > > > > > > > > >> all its features. We can use listeners or continuous > queries > > > for > > > > > > > > >> deployment synchronizations. > > > > > > > > >> > > > > > > > > >> Why do you want using the discovery layer for that? > > > > > > > > >> > > > > > > > > >> One more thing: we can use baseline approach for services, > > > that > > > > > > means > > > > > > > > >> *IgniteService.deploy()* returns ready to work service > after > > > > > > > > >> deployment on baseline nodes and deploy to other nodes on > > > > demand, > > > > > > for > > > > > > > > >> example when deployed service's loading will be hight. > > > > > > > > >> > > > > > > > > >> About versioning, maybe there is sense to extend public > API: > > > > > > > > >> IgniteServices.service(name, *version*)? > > > > > > > > >> > > > > > > > > >> At first deployment, we can compute service's hashcode > (just > > > for > > > > > an > > > > > > > > >> example) and store it, after new deployment request for > > > services > > > > > > with > > > > > > > > >> an existing name we will compute new service's hashcode > and > > > > > compare > > > > > > > > >> them if they have different hashcodes that we will deploy > > new > > > > > > service > > > > > > > > >> as service with a different version. > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> On Fri, Mar 23, 2018 at 10:03 PM, Denis Magda < > > > > dma...@apache.org> > > > > > > > > wrote: > > > > > > > > >> > Denis, > > > > > > > > >> > > > > > > > > > >> > Thanks for the extensive analysis. There is a vast room > > for > > > > > > > > optimizations > > > > > > > > >> > on the service grid side. > > > > > > > > >> > > > > > > > > > >> > Yakov, Sam, Alex G., > > > > > > > > >> > > > > > > > > > >> > How do you like the idea of the usage of discovery > > protocol > > > > for > > > > > > the > > > > > > > > >> service > > > > > > > > >> > grid system messages exchange? Any pitfalls? > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > -- > > > > > > > > >> > Denis > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > On Fri, Mar 23, 2018 at 8:01 AM, Denis Mekhanikov < > > > > > > > > dmekhani...@gmail.com > > > > > > > > >> > > > > > > > > > >> > wrote: > > > > > > > > >> > > > > > > > > > >> >> Igniters, > > > > > > > > >> >> > > > > > > > > >> >> I'd like to start a discussion on Ignite service grid > > > > redesign. > > > > > > > > >> >> We have a number of problems in our current > architecture, > > > > that > > > > > > have > > > > > > > > to > > > > > > > > >> be > > > > > > > > >> >> addressed. > > > > > > > > >> >> > > > > > > > > >> >> Here are the most severe ones: > > > > > > > > >> >> > > > > > > > > >> >> One of them is lack of guarantee, that service is > > > > successfully > > > > > > > > deployed > > > > > > > > >> and > > > > > > > > >> >> ready for work by the time, when > > *IgniteService.deploy*()* > > > > > > methods > > > > > > > > >> return. > > > > > > > > >> >> Furthermore, if an exception is thrown from > > *Service.init() > > > > > > > *method, > > > > > > > > >> then > > > > > > > > >> >> the deploying side is not able to receive it, or even > > > > > understand, > > > > > > > > that > > > > > > > > >> >> service is in unusable state. > > > > > > > > >> >> So, you may end up in such situation, when you > deployed a > > > > > service > > > > > > > > >> without > > > > > > > > >> >> receiving any errors, then called a service's method, > and > > > > hung > > > > > > > > >> indefinitely > > > > > > > > >> >> on this invocation. > > > > > > > > >> >> JIRA ticket: > > > > https://issues.apache.org/jira/browse/IGNITE-3392 > > > > > > > > >> >> > > > > > > > > >> >> Another problem is locking during service deployment on > > > > > unstable > > > > > > > > >> topology. > > > > > > > > >> >> This issue is caused by missing updates in continuous > > query > > > > > > > > listeners on > > > > > > > > >> >> the internal cache. > > > > > > > > >> >> It is hard to reproduce, but it happens sometimes. We > > > > shouldn't > > > > > > > allow > > > > > > > > >> such > > > > > > > > >> >> possibility, that deployment methods hang without > saying > > > > > > anything. > > > > > > > > >> >> JIRA ticket: > > > > https://issues.apache.org/jira/browse/IGNITE-6259 > > > > > > > > >> >> > > > > > > > > >> >> I think, we should change the deployment procedure to > > make > > > it > > > > > > more > > > > > > > > >> >> reliable. > > > > > > > > >> >> Moving from operating over internal replicated service > > > cache > > > > to > > > > > > > > sending > > > > > > > > >> >> custom discovery events seems to be a good idea. > > > > > > > > >> >> Service deployment may trigger a discovery event, that > > will > > > > > make > > > > > > > > chosen > > > > > > > > >> >> nodes deploy the service, and the same event will > notify > > > > other > > > > > > > nodes > > > > > > > > >> about > > > > > > > > >> >> the deployed service instances. > > > > > > > > >> >> It will eliminate the need for distributed transactions > > on > > > > the > > > > > > > > internal > > > > > > > > >> >> replicated system cache, and make the service > deployment > > > > > protocol > > > > > > > > more > > > > > > > > >> >> transparent. > > > > > > > > >> >> > > > > > > > > >> >> There are a few points, that should be taken into > account > > > > > though. > > > > > > > > >> >> > > > > > > > > >> >> First of all, we can't wait for services to be deployed > > and > > > > > > > > initialised > > > > > > > > >> in > > > > > > > > >> >> the discovery thread. > > > > > > > > >> >> So, we need to make notification about service > deployment > > > > > result > > > > > > > > >> >> asynchronous, presumably over communication protocol. > > > > > > > > >> >> I can think of a procedure similar to the current > > exchange > > > > > > > protocol, > > > > > > > > >> when > > > > > > > > >> >> service deployment is initialised with an initial > > discovery > > > > > > > message, > > > > > > > > >> >> followed by asynchronous notifications from the hosting > > > > servers > > > > > > > over > > > > > > > > >> >> communication. And finally, one more discovery message > > will > > > > > > notify > > > > > > > > all > > > > > > > > >> >> nodes about the service deployment result and location > of > > > the > > > > > > > > deployed > > > > > > > > >> >> service instances. Coordinator will be responsible for > > > > > collecting > > > > > > > of > > > > > > > > the > > > > > > > > >> >> deployment results in this scheme. > > > > > > > > >> >> > > > > > > > > >> >> Another problem is failover in case, when some nodes > fail > > > > > during > > > > > > > > >> deployment > > > > > > > > >> >> or further work. > > > > > > > > >> >> The following cases should be handled: > > > > > > > > >> >> > > > > > > > > >> >> 1. coordinator failure during deployment; > > > > > > > > >> >> 2. failure of nodes, that were chosen to host the > > > service, > > > > > > > during > > > > > > > > >> >> deployment; > > > > > > > > >> >> 3. failure of nodes, that contain deployed services, > > > after > > > > > the > > > > > > > > >> >> deployment. > > > > > > > > >> >> > > > > > > > > >> >> The first case may be resolved by either continuation > of > > > > > > deployment > > > > > > > > >> with a > > > > > > > > >> >> new coordinator, or by cancelling it. > > > > > > > > >> >> The second case will require another node to be chosen > > and > > > > > > > notified. > > > > > > > > >> Maybe > > > > > > > > >> >> another discovery message will be needed. > > > > > > > > >> >> The third case will require redeployment, so > coordinator > > > > should > > > > > > > track > > > > > > > > >> >> topology changes and redeploy failed services. > > > > > > > > >> >> > > > > > > > > >> >> Another good improvement would be service versioning. > > This > > > > > matter > > > > > > > was > > > > > > > > >> >> already discussed in another thread: > > > > > > > > >> >> > > > > > > > > >> > > > > > > > > http://apache-ignite-developers.2346864.n4.nabble. > > > > > > > com/Service-versioning- > > > > > > > > >> >> td20858.html > > > > > > > > >> >> Let's resume this discussion and state the final > decision > > > > here. > > > > > > > > >> >> This feature is closely connected to peer class > loading, > > > > which > > > > > is > > > > > > > not > > > > > > > > >> >> working for services currently. > > > > > > > > >> >> So, service versioning should be implemented along with > > > peer > > > > > > class > > > > > > > > >> loading. > > > > > > > > >> >> JIRA ticket for versioning: > > > > > > > > >> >> https://issues.apache.org/jira/browse/IGNITE-6069 > > > > > > > > >> >> Peer class loading: https://issues.apache.org/ > > > > > > > jira/browse/IGNITE-975 > > > > > > > > >> >> > > > > > > > > >> >> Please share your thoughts. Constructive criticism is > > > highly > > > > > > > > >> appreciated. > > > > > > > > >> >> > > > > > > > > >> >> Denis > > > > > > > > >> >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> -- > > > > > > > > >> Best Regards, Vyacheslav D. > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > Best Regards, Vyacheslav D. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
