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https://issues.apache.org/jira/browse/HDFS-17150?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaoqiao He resolved HDFS-17150.
--------------------------------
    Fix Version/s: 3.4.0
     Hadoop Flags: Reviewed
       Resolution: Fixed

> EC: Fix the bug of failed lease recovery.
> -----------------------------------------
>
>                 Key: HDFS-17150
>                 URL: https://issues.apache.org/jira/browse/HDFS-17150
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Shuyan Zhang
>            Assignee: Shuyan Zhang
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 3.4.0
>
>
> If the client crashes without writing the minimum number of internal blocks 
> required by the EC policy, the lease recovery process for the corresponding 
> unclosed file may continue to fail. Taking RS(6,3) policy as an example, the 
> timeline is as follows:
> 1. The client writes some data to only 5 datanodes;
> 2. Client crashes;
> 3. NN fails over;
> 4. Now the result of `uc.getNumExpectedLocations()` completely depends on 
> block report, and there are 5 datanodes reporting internal blocks;
> 5. When the lease expires hard limit, NN issues a block recovery command;
> 6. The datanode checks the command and finds that the number of internal 
> blocks is insufficient, resulting in an error and recovery failure;
> 7. The lease expires hard limit again, and NN issues a block recovery command 
> again, but the recovery fails again......
> When the number of internal blocks written by the client is less than 6, the 
> block group is actually unrecoverable. We should equate this situation to the 
> case where the number of replicas is 0 when processing replica files, i.e., 
> directly remove the last block group and close the file.
>  



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