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From "Jiafu Jiang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ZOOKEEPER-3231) Purge task may lost data when we have many invalid snapshots.
Date Sat, 29 Dec 2018 04:08:00 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-3231?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jiafu Jiang updated ZOOKEEPER-3231:
-----------------------------------
    Description: 
I read the ZooKeeper source code, and I find the purge task use FileTxnSnapLog#findNRecentSnapshots
to find snapshots, but the method does not check whether the snapshots are valid.

Consider a worse case, a ZooKeeper server may have many invalid snapshots, and when a purge
task begins, it will use the zxid in the last snapshot's name to purge old snapshots and transaction
logs, then we may lost data. 

I think we should use FileSnap#findNValidSnapshots(int) instead of FileSnap#findNRecentSnapshots
in FileTxnSnapLog#findNRecentSnapshots, but I am not sure.

 

  was:
I read the ZooKeeper source code, and I find the purge task use FileTxnSnapLog#findNRecentSnapshots
to find snapshots, but the method does not check whether the snapshots are valid.

Consider a worse case, a ZooKeeper server may have many invalid snapshots, and when a purge
task begins, it will use the zxid in the last snapshot's name to purge old snapshots and transaction
logs, then we may lost data. 

I think we should use FileSnap#findNValidSnapshots(int) instead of FileSnap#findNRecentSnapshots
in FileTxnSnapLog#findNRecentSnapshots. I am not sure.

 


>  Purge task may lost data when we have many invalid snapshots.
> --------------------------------------------------------------
>
>                 Key: ZOOKEEPER-3231
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3231
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: server
>    Affects Versions: 3.5.4, 3.4.13
>            Reporter: Jiafu Jiang
>            Priority: Major
>
> I read the ZooKeeper source code, and I find the purge task use FileTxnSnapLog#findNRecentSnapshots
to find snapshots, but the method does not check whether the snapshots are valid.
> Consider a worse case, a ZooKeeper server may have many invalid snapshots, and when a
purge task begins, it will use the zxid in the last snapshot's name to purge old snapshots
and transaction logs, then we may lost data. 
> I think we should use FileSnap#findNValidSnapshots(int) instead of FileSnap#findNRecentSnapshots
in FileTxnSnapLog#findNRecentSnapshots, but I am not sure.
>  



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