[jira] [Commented] (IGNITE-18132) Introduce scale down scheduler

["Alexander Lapin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-18132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17685983#comment-17685983 ] 

Alexander Lapin commented on IGNITE-18132:
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[~maliev] LGTM

> Introduce scale down scheduler
> ------------------------------
>
>                 Key: IGNITE-18132
>                 URL: https://issues.apache.org/jira/browse/IGNITE-18132
>             Project: Ignite
>          Issue Type: Improvement
>            Reporter: Alexander Lapin
>            Assignee: Mirza Aliev
>            Priority: Major
>              Labels: ignite-3
>          Time Spent: 2h 10m
>  Remaining Estimate: 0h
>
> h3. Motivation
> Surprisingly it's a follow up of an Introduce scale up scheduler
> Following logic should be implemented 
> |-1|start Node A;
> start Node B;
> start Node C;
> CREATE ZONE zone1 WITH   DATA_NODES_AUTO_ADJUST_{*}SCALE_UP{*} = 300, DATA_NODES_AUTO_ADJUST_{*}SCALE_DOWN{*}= 300_000;
> CREATE TABLE Accounts … WITH  PRIMARY_ZONE = zone1 |User starts three Ignite nodes A, B, C and creates table Accounts specifying scale up auto adjust timeout as 300 seconds. Accounts table is created on current topology, meaning that <Transaction>.dataNodes = [A,B,C]|
> |0|start Node D ->
>     Node D join/validation ->
>     D enters logical topology ->
>     logicalTopology.onNodeAdded(Node D) ->
>     scale_up_auto_adjust(300) timer is
>     scheduled for the <Accounts> table.|At time 0 seconds the user starts one more Ignite node D, that joins the cluster. On entering logical topology the onNodeAdded event is fired. This event, schedules a timer of 300 seconds for table Accounts after which the dataNodes of that table will be recalculated from [A,B,C] to [A,B,C,D]|
> |100|stop Node C -> 
>     scale_{*}down{*}_auto_adjust(300_000) timer
>     is scheduled for the <Accounts> table.|At 100 seconds the user stops Node C (or it painfully dies). TableManager detects onNodeLeft(Node C) event and starts scale_down time for 300_000 seconds for table <Accounts>. Please pay attention that the node left doesn’t affect the scale_up timer.|
> |250|start Node E ->
>     scale_up_auto_adjust(300) timer is
>     {*}re-{*}scheduled for the <Accounts> table.|At 250 seconds Node E is added, that re-schedules scale_up_auto_adjust timer for another 300 seconds. The important part here is that adding the node doesn’t change scale_down time only scale_up one.|
> |550|scale_up_auto_adjust fired ->
>     set table.<Accounts>.dataNodes = 
>     [NodeA, NodeB, {*}NodeC{*}, Node D, Node E]|At 550 seconds scale_up_time is fired, that leads to <Transaction>dataNodes recalculation by attaching the nodes that were added to logical topology - Nodes D and E in the given example. Please pay attention that despite the fact there's no Node C in logical topology it still takes its place in <Transaction>.dataNodes. |
> |300100|*scale_down_auto_adjust fired* -> 
>     set table.<Accounts>.dataNodes = 
>     [NodeA, NodeB, Node D, Node E]|At 300_100 seconds scale_down_auto_adjust timer is fired, that leads to removing Node C from <Transaction>.dataNodes.|
> h3. Definition of Done
>  * DataNodes recalculation transitively triggered by node left event is delayed for dataNodesAutoAdjustScale{*}Down{*} value.
>  * In case of new scale down toplogy event, existing scale down timers should be re-scheduled.
>  * Scale up timers should not be affected.
> h3. Implementation Notes
> As as for scale up.



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