[jira] [Closed] (JAMES-3265) Investigate Slow IMAP SELECT (26 minutes +)

["Benoit Tellier (Jira)" <se...@james.apache.org>]

     [ https://issues.apache.org/jira/browse/JAMES-3265?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benoit Tellier closed JAMES-3265.
---------------------------------
    Resolution: Fixed

All mentionned PR are merged

> Investigate Slow IMAP SELECT (26 minutes +)
> -------------------------------------------
>
>                 Key: JAMES-3265
>                 URL: https://issues.apache.org/jira/browse/JAMES-3265
>             Project: James Server
>          Issue Type: Task
>          Components: cassandra, IMAPServer
>    Affects Versions: master
>            Reporter: Benoit Tellier
>            Priority: Major
>              Labels: perf
>             Fix For: 3.6.0
>
>         Attachments: Capture_d_écran_de_2020-06-22_11-42-01.png, Capture_d_écran_de_2020-06-22_11-48-28.png
>
>
> Using glowroot APM on Linagora run instances, I noticed some select commands takes around 20 minutes.
> A performance review shows thousands of MODSEQ updates undermines the performance.
> {code:java}
> Transaction type: IMAP
> Transaction name: IMAP processor : org.apache.james.imap.processor.SelectProcessor
> Start: 2020-06-22 2:28:04.433 am (+07:00)
> Duration: 1,618,718.3 milliseconds
> {code}
> I noticed a high allocation of new ModSeq (28.000 instead of 1) due to uid set disjonction.
> I believe a solution would be to implement a new MessageMapper method:
> Mono<Void> removeRecentFlags(Mailbox mbox);
> That would enable some Cassandra query optimizations...
> # DOD 
>  - unlock significant performance improvments for such queries (x100)
> Attached you will find the query stats and flame graph backing up the analysis.



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