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https://issues.apache.org/jira/browse/FLUME-2155?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Brock Noland updated FLUME-2155:
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    Attachment: FLUME-FC-SLOW-REPLAY-FIX-1.patch
                FLUME-FC-SLOW-REPLAY-1.patch

> Improve replay time
> -------------------
>
>                 Key: FLUME-2155
>                 URL: https://issues.apache.org/jira/browse/FLUME-2155
>             Project: Flume
>          Issue Type: Bug
>            Reporter: Hari Shreedharan
>            Assignee: Hari Shreedharan
>         Attachments: 10000-20000, 100000-110000, 300000-310000, 
> 700000-710000, FLUME-2155-initial.patch, FLUME-2155.patch, 
> FLUME-FC-SLOW-REPLAY-1.patch, FLUME-FC-SLOW-REPLAY-FIX-1.patch, 
> SmartReplay.pdf, SmartReplay1.1.pdf, fc-test.patch
>
>
> File Channel has scaled so well that people now run channels with sizes in 
> 100's of millions of events. Turns out, replay can be crazy slow even between 
> checkpoints at this scale - because of the remove() method in FlumeEventQueue 
> moving every pointer that follows the one being removed (1 remove causes 99 
> million+ moves for a channel of 100 million!). There are several ways of 
> improving - one being move at the end of replay - sort of like a compaction. 
> Another is to use the fact that all removes happen from the top of the queue, 
> so move the first "k" events out to hashset and remove from there - we can 
> find k using the write id of the last checkpoint and the current one. 



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