[jira] [Closed] (JAMES-4140) Ability to shape IMAP applicative traffic

     [ https://issues.apache.org/jira/browse/JAMES-4140?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benoit Tellier closed JAMES-4140.
---------------------------------
    Resolution: Fixed

Merged

> Ability to shape IMAP applicative traffic
> -----------------------------------------
>
>                 Key: JAMES-4140
>                 URL: https://issues.apache.org/jira/browse/JAMES-4140
>             Project: James Server
>          Issue Type: Improvement
>          Components: IMAPServer
>            Reporter: Benoit Tellier
>            Priority: Major
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> h2. Why?
> Some clients (Outlook) resynchronizes with an infinite loop on folders, SELECTing them all one by one.
> This naive implementation results in an absurdly high workload.
> Optimizing the given commands would not be a solution as it would only result in a higher workload as requests would be even more frequent.
> Additionnally, being able to regulate traffic, imposing delays to clients that exceeds their QoS, seems like a desirable feature of a production-ready email server.
> h2. How?
> Implement a Netty ChannelInboundHandlerAdapter to be placed between IMAP command parsing and execution adding delays prior command execution as needed.
> h3. Configuration proposal
> The user can declare the list of commands on which throttling needs to be tracked and for each:
>  - `thresholdCount`: below this number of occurrence, no throttling is applied. Integer.
>  - `additionalDelayPerOperation`: delay to be applied when exceeding the threshold. The delay is cumulative and thus
>  would always increase. Duration.
>  - `observationPeriod`: the count of observed commands is reset after this period thus stopping delays. Duration.
>  - `maxDelay`: maximum value the client will be delayed for.
> Sample configuration:
> {code:xml}
> <imapserver>
>   <!-- ... -->
>   <perSessionCommandThrottling>
>     <select>
>       <thresholdCount>25</thresholdCount>
>       <additionalDelayPerOperation>2ms</additionalDelayPerOperation>
>       <observationPeriod>10m</observationPeriod>
>       <maxDelay>1s</maxDelay>
>     </select>
>     <append>
>       <thresholdCount>5</thresholdCount>
>       <additionalDelayPerOperation>10ms</additionalDelayPerOperation>
>       <observationPeriod>5m</observationPeriod>
>       <maxDelay>2s</maxDelay>
>     </append>
>   </perSessionCommandThrottling>
> </imapserver>
> {code}



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