[jira] [Updated] (FLUME-1516) Write Dual Checkpoints to avoid replays

["Hari Shreedharan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLUME-1516?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hari Shreedharan updated FLUME-1516:
------------------------------------

    Attachment: FLUME-1516.patch
    
> Write Dual Checkpoints to avoid replays
> ---------------------------------------
>
>                 Key: FLUME-1516
>                 URL: https://issues.apache.org/jira/browse/FLUME-1516
>             Project: Flume
>          Issue Type: Improvement
>          Components: Channel
>    Affects Versions: v1.3.0
>            Reporter: Brock Noland
>            Assignee: Hari Shreedharan
>         Attachments: FLUME-1516.patch
>
>
> Per the LFS paper (http://www.cs.berkeley.edu/~brewer/cs262/LFS.pdf) we can write two checkpoints to avoid replaying the logs in the case we crash/shutdown while writing a checkpoint.
> Section 4:
> "In order to handle a crash during a checkpoint operation there are actually two checkpoint regions, and checkpoint operations alternate between them. The checkpoint time is in the last block of the checkpoint so if the checkpoint fails the time will not be updated. During reboot, the system reads both checkpoint regions and uses the one with the most recent time."

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