[jira] [Resolved] (IGNITE-7182) Slow sorting of pages collection on checkpoint begin can cause zero dropdown even with throttling enabled

["Dmitriy Pavlov (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-7182?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dmitriy Pavlov resolved IGNITE-7182.
------------------------------------
    Fix Version/s:     (was: 2.8)
       Resolution: Won't Fix

Benchmarking does not show any performance boost from another sorting

> Slow sorting of pages collection on checkpoint begin can cause zero dropdown even with throttling enabled
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: IGNITE-7182
>                 URL: https://issues.apache.org/jira/browse/IGNITE-7182
>             Project: Ignite
>          Issue Type: Improvement
>          Components: persistence
>    Affects Versions: 2.3
>            Reporter: Ivan Rakov
>            Assignee: Dmitriy Pavlov
>            Priority: Major
>
> Tests show that GridCacheDatabaseSharedManager#splitAndSortCpPagesIfNeeded call can last several seconds on nodes with big amount of memory (>10GB). We should optimize sorting algorithm, possibly making it multithreaded.
> Another option to make pages write throttling more smooth is to get rid of this heuristic:
> {noformat}
>                 // Starting with 0.05 to avoid throttle right after checkpoint start
>                 // 7/12 is maximum ratio of dirty pages
>                 dirtyRatioThreshold = (dirtyRatioThreshold * 0.95 + 0.05) * 7 / 12;
> {noformat}
> We should replace "magic" lower bound 0.05 * 7 / 12 with the real percentage of dirty pages at the moment of GridCacheDatabaseSharedManager.Checkpointer#markCheckpointBegin call return.



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