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https://issues.apache.org/jira/browse/HDFS-8344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14634172#comment-14634172
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Haohui Mai commented on HDFS-8344:
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-1. Can you please revert the commit?
I'm concerned with the complexity associated with the commit as well as the
difficulty for the users to choose the right configuration. It's an internal
implementation detail and it should not be exposed to users whenever it's
possible. We intentionally keep the soft and hard limit not configurable to
avoid the users shooting their foot.
bq. The datanode might be busy and recovery may fail the first time.
That's exactly what the hard limit / retries of leases is designed for. Again
this is only one type of internal implementation towards the solution. The
detail should not be exposed to the users.
> NameNode doesn't recover lease for files with missing blocks
> ------------------------------------------------------------
>
> Key: HDFS-8344
> URL: https://issues.apache.org/jira/browse/HDFS-8344
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.7.0
> Reporter: Ravi Prakash
> Assignee: Ravi Prakash
> Fix For: 2.8.0
>
> Attachments: HDFS-8344.01.patch, HDFS-8344.02.patch,
> HDFS-8344.03.patch, HDFS-8344.04.patch, HDFS-8344.05.patch,
> HDFS-8344.06.patch, HDFS-8344.07.patch
>
>
> I found another\(?) instance in which the lease is not recovered. This is
> reproducible easily on a pseudo-distributed single node cluster
> # Before you start it helps if you set. This is not necessary, but simply
> reduces how long you have to wait
> {code}
> public static final long LEASE_SOFTLIMIT_PERIOD = 30 * 1000;
> public static final long LEASE_HARDLIMIT_PERIOD = 2 *
> LEASE_SOFTLIMIT_PERIOD;
> {code}
> # Client starts to write a file. (could be less than 1 block, but it hflushed
> so some of the data has landed on the datanodes) (I'm copying the client code
> I am using. I generate a jar and run it using $ hadoop jar TestHadoop.jar)
> # Client crashes. (I simulate this by kill -9 the $(hadoop jar
> TestHadoop.jar) process after it has printed "Wrote to the bufferedWriter"
> # Shoot the datanode. (Since I ran on a pseudo-distributed cluster, there was
> only 1)
> I believe the lease should be recovered and the block should be marked
> missing. However this is not happening. The lease is never recovered.
> The effect of this bug for us was that nodes could not be decommissioned
> cleanly. Although we knew that the client had crashed, the Namenode never
> released the leases (even after restarting the Namenode) (even months
> afterwards). There are actually several other cases too where we don't
> consider what happens if ALL the datanodes die while the file is being
> written, but I am going to punt on that for another time.
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