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From Vyacheslav Daradur <daradu...@gmail.com>
Subject Re: Service Grid new design overview
Date Thu, 30 Aug 2018 12:04:01 GMT
Hi Igniters!

I had a private talk about new Service Grid design with: Alexey
Goncharuk, Vladimir Ozerov, Denis Mekhanikov, Nikolay Izhikov, Anton
Vinogradov and I'd like to share results.

Design looks good in general, but we have decided to improve the
unified flow of requests processing as follows - when any node
received request on deploying, a node should calculate assignments
yourself and deploys it if needed, then sends the result to the
coordinator instead of waiting for assignments from the coordinator.

For this change, we should make our service's assignments function
*determined*, that means the function will return the same results for
the same arguments at any node.

We all agreed with this change because it allows us to reduce messages
for handling each request and making the solution more flexible.

On Tue, Aug 28, 2018 at 12:26 AM Dmitriy Setrakyan
<dsetrakyan@apache.org> wrote:
>
> Agree with Val. I think all users would expect that a service is restarted
> upon a node or cluster restart. Let's make sure we preserve this behavior.
>
> D.
>
> On Fri, Aug 24, 2018 at 4:17 PM, Valentin Kulichenko <
> valentin.kulichenko@gmail.com> wrote:
>
> > Guys,
> >
> > I believe we should preserve the behavior that we have now. What happens to
> > services if we restart a persistent cluster running 2.6? Are services
> > recreated or not? If YES, we should make sure the same happens after
> > redesign. Would be even better if we preserve compatibility, i.e. allow
> > seamless upgrade from older version that uses system cache to newer version
> > that uses disco messages for service deployment. If NO, it's much easier
> > and we can leave it as is for now. However, eventually would be great to
> > have an option to persist services and redeploy them after cluster restart.
> >
> > -Val
> >
> > On Fri, Aug 24, 2018 at 2:51 PM Dmitriy Pavlov <dpavlov.spb@gmail.com>
> > wrote:
> >
> > > Denis M. & Val please share your vision about this topic.
> > >
> > > пт, 24 авг. 2018 г. в 15:52, Vyacheslav Daradur <daradurvs@gmail.com>:
> > >
> > > > Nick, Antron, thank you for stepping in.
> > > >
> > > > AFAIK, Ignite cluster can move its state to a new version of Ignite
> > > > using persistence only.
> > > >
> > > > Since Ignite v.2.3 persistence is configured on a memory region and
> > > > system memory region is not persistence, that means the system
> > > > (utility) cache will not be recovered on cluster restart.
> > > >
> > > > Here is a ticket which describes the same issue:
> > > > https://issues.apache.org/jira/browse/IGNITE-6629
> > > >
> > > > > BTW, Is proposed solution provides the guarantee that services will
> > be
> > > > > redeployed after each cluster restart since now we're not using the
> > > > cache?
> > > >
> > > > No, only services described in IgniteConfiguration will be deployed at
> > > > node startup as well as now.
> > > >
> > > > Am I wrong in something?
> > > > On Thu, Aug 23, 2018 at 5:59 PM Anton Vinogradov <av@apache.org>
> > wrote:
> > > > >
> > > > > Vyacheslav.
> > > > >
> > > > > It looks like we able to restart all services on grid startup from
> > old
> > > > > definitions (inside cache) in case persistence turned on.
> > > > > Se no problems to provide such automated migration case.
> > > > > Also, we can test it using compatibility framework.
> > > > >
> > > > > BTW, Is proposed solution provides the guarantee that services will
> > be
> > > > > redeployed after each cluster restart since now we're not using the
> > > > cache?
> > > > >
> > > > > чт, 23 авг. 2018 г. в 15:21, Nikolay Izhikov <nizhikov@apache.org>:
> > > > >
> > > > > > Hello, Vyacheslav.
> > > > > >
> > > > > > Thanks, for sharing your design.
> > > > > >
> > > > > > > I have a question about services migration from AI 2.6
to a new
> > > > solution
> > > > > >
> > > > > > Can you describe consequences of not having migration solution?
> > > > > > What will happen on the user side?
> > > > > >
> > > > > >
> > > > > > В Чт, 23/08/2018 в 14:44 +0300, Vyacheslav Daradur пишет:
> > > > > > > Hi, Igniters!
> > > > > > >
> > > > > > > I’m working on Service Grid redesign tasks and design
seems to be
> > > > > > finished.
> > > > > > >
> > > > > > > The main goal of Service Grid redesign is to provide missed
> > > > guarantees:
> > > > > > > - Synchronous services deployment/undeployment;
> > > > > > > - Failover on coordinator change;
> > > > > > > - Propagation of deployments errors across the cluster;
> > > > > > > - Introduce of a deployment failures policy;
> > > > > > > - Prevention of deployments initiators hangs while deployment;
> > > > > > > - etc.
> > > > > > >
> > > > > > > I’d like to ask the community their thoughts about the
proposed
> > > > design
> > > > > > > to be sure that all important things have been considered.
> > > > > > >
> > > > > > > Also, I have a question about services migration from AI
2.6 to a
> > > new
> > > > > > > solution. It’s very hard to provide tools for users migration,
> > > > because
> > > > > > > of significant changes. We don’t use utility cache anymore.
> > Should
> > > we
> > > > > > > spend time on this?
> > > > > > >
> > > > > > > I’ve prepared a definition of new Service Grid design,
it’s
> > > described
> > > > > > below:
> > > > > > >
> > > > > > > *OVERVIEW*
> > > > > > >
> > > > > > > All nodes (servers and clients) are able to host services,
but
> > the
> > > > > > > client nodes are excluded from service deployment by default.
The
> > > > only
> > > > > > > way to deploy service on clients nodes is to specify node
filter
> > in
> > > > > > > ServiceConfiguration.
> > > > > > >
> > > > > > > All deployed services are identified internally by “serviceId”
> > > > > > > (IgniteUuid). This allows us to build a base for such features
as
> > > hot
> > > > > > > redeployment and service’s versioning. It’s important
to have the
> > > > > > > ability to identify and manage services with the same name,
but
> > > > > > > different version.
> > > > > > >
> > > > > > > All actions on service’s state change are processed according
to
> > > > unified
> > > > > > flow:
> > > > > > > 1) Initiator sends over disco-spi a request to change service
> > state
> > > > > > > [deploy, undeploy] DynamicServicesChangeRequestBatchMessage
> > which
> > > > will
> > > > > > > be stored by all server nodes in own queue to be processed,
if
> > > > > > > coordinator failed, at new coordinator;
> > > > > > > 2) Coordinator calculates assignments and defines actions
in a
> > new
> > > > > > > message ServicesAssignmentsRequestMessage and sends it
over
> > > disco-spi
> > > > > > > to be processed by all nodes;
> > > > > > > 3) All nodes apply actions and build single map message
> > > > > > > ServicesSingleMapMessage that contains services id and
amount of
> > > > > > > instances were deployed on this single node and sends the
message
> > > > over
> > > > > > > comm-spi to coordinator (p2p);
> > > > > > > 4) Once coordinator receives all single map messages then
it
> > builds
> > > > > > > ServicesFullMapMessage that contains services deployments
across
> > > the
> > > > > > > cluster and sends message over disco-spi to be processed
by all
> > > > nodes;
> > > > > > >
> > > > > > > *MESSAGES*
> > > > > > >
> > > > > > > class DynamicServicesChangeRequestBatchMessage {
> > > > > > >     Collection<DynamicServiceChangeRequest> reqs;
> > > > > > > }
> > > > > > >
> > > > > > > class DynamicServiceChangeRequest {
> > > > > > >     IgniteUuid srvcId; // Unique service id (generates
to deploy,
> > > > > > > existing used to undeploy)
> > > > > > >     ServiceConfiguration cfg; // Empty in case of undeploy
> > > > > > >     byte flags; // Change’s types flags [deploy, undeploy,
etc.]
> > > > > > > }
> > > > > > >
> > > > > > > class ServicesAssignmentsRequestMessage {
> > > > > > >     ServicesDeploymentExchangeId exchId;
> > > > > > >     Map<IgniteUuid, Map<UUID, Integer>> srvcsToDeploy;
// Deploy
> > > and
> > > > > > reassign
> > > > > > >     Collection<IgniteUuid> srvcsToUndeploy;
> > > > > > > }
> > > > > > >
> > > > > > > class ServicesSingleMapMessage {
> > > > > > >     ServicesDeploymentExchangeId exchId;
> > > > > > >     Map<IgniteUuid, ServiceSingleDeploymentsResults>
results;
> > > > > > > }
> > > > > > >
> > > > > > > class ServiceSingleDeploymentsResults {
> > > > > > >     int cnt; // Deployed instances count, 0 in case of
undeploy
> > > > > > >     Collection<byte[]> errors; // Serialized exceptions
to avoid
> > > > > > > issues at spi-level
> > > > > > > }
> > > > > > >
> > > > > > > class ServicesFullMapMessage  {
> > > > > > >     ServicesDeploymentExchangeId exchId;
> > > > > > >     Collection<ServiceFullDeploymentsResults> results;
> > > > > > > }
> > > > > > >
> > > > > > > class ServiceFullDeploymentsResults {
> > > > > > >     IgniteUuid srvcId;
> > > > > > >     Map<UUID, ServiceSingleDeploymentsResults> results;
// Per
> > node
> > > > > > > }
> > > > > > >
> > > > > > > class ServicesDeploymentExchangeId {
> > > > > > >     UUID nodeId; // Initiated, joined or failed node id
> > > > > > >     int evtType; // EVT_NODE_[JOIN/LEFT/FAILED],
> > > > EVT_DISCOVERY_CUSTOM_EVT
> > > > > > >     AffinityTopologyVersion topVer;
> > > > > > >     IgniteUuid reqId; // Unique id of custom discovery
message
> > > > > > > }
> > > > > > >
> > > > > > > *COORDINATOR CHANGE*
> > > > > > >
> > > > > > > All server nodes handle requests of service’s state changes
and
> > put
> > > > it
> > > > > > > into deployment queue, but only coordinator process them.
If
> > > > > > > coordinator left or fail they will be processed on new
> > coordinator.
> > > > > > >
> > > > > > > *TOPOLOGY CHANGE*
> > > > > > >
> > > > > > > Each topology change (NODE_JOIN/LEFT/FAILED event) causes
> > service's
> > > > > > > states deployment task. Assignments will be recalculated
and
> > > applied
> > > > > > > for each deployed service.
> > > > > > >
> > > > > > > *CLUSTER ACTIVATION/DEACTIVATION*
> > > > > > >
> > > > > > > - On deactivation:
> > > > > > >     * local services are being undeployed;
> > > > > > >     * requests are not handling (including deployment /
> > > > undeployment);
> > > > > > > - On activation:
> > > > > > >     * local services are being redeployed;
> > > > > > >     * requests are handling as usual;
> > > > > > >
> > > > > > > *RELATED LINKS*
> > > > > > >
> > > > > > >
> > > > > >
> > > >
> > > https://cwiki.apache.org/confluence/display/IGNITE/IEP-
> > 17%3A+Oil+Change+in+Service+Grid
> > > > > > >
> > > > > >
> > > >
> > > http://apache-ignite-developers.2346864.n4.nabble.
> > com/Service-grid-redesign-td28521.html
> > > > > > >
> > > > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > Best Regards, Vyacheslav D.
> > > >
> > >
> >



-- 
Best Regards, Vyacheslav D.

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