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https://issues.apache.org/jira/browse/HDFS-4882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14215089#comment-14215089
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Jing Zhao edited comment on HDFS-4882 at 11/17/14 8:04 PM:
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bq. Is there any reason we can't simply recover the lease anyway, even though
the minimal replication has not been met? There are a lot of cases where we
just can't get to the minimum replication (i.e. 1-node cluster, etc.). I don't
see a lot of value in letting these leases linger forever.
I agree with [~cmccabe] here. I do not think we should block anything just
because the penultimate block cannot reach the minimum replication. To me this
is similar with the scenario that one block of the file is missing/corrupted
(even if the min replication is 1). For append case since we do not append data
directly to the penultimate block thus I think should be ok.
was (Author: jingzhao):
bq. Is there any reason we can't simply recover the lease anyway, even though
the minimal replication has not been met? There are a lot of cases where we
just can't get to the minimum replication (i.e. 1-node cluster, etc.). I don't
see a lot of value in letting these leases linger forever.
I agree with [~cmccabe] here. I do not think we should block anything just
because the penultimate block cannot reach the minimum replication. To me this
is similar with the scenario that one block of the file is missing/corrupted.
For append case since we do not append data directly to the penultimate block
thus I think should be ok.
> Namenode LeaseManager checkLeases() runs into infinite loop
> -----------------------------------------------------------
>
> Key: HDFS-4882
> URL: https://issues.apache.org/jira/browse/HDFS-4882
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client, namenode
> Affects Versions: 2.0.0-alpha, 2.5.1
> Reporter: Zesheng Wu
> Assignee: Ravi Prakash
> Priority: Critical
> Attachments: 4882.1.patch, 4882.patch, 4882.patch, HDFS-4882.1.patch,
> HDFS-4882.2.patch, HDFS-4882.3.patch, HDFS-4882.4.patch, HDFS-4882.patch
>
>
> Scenario:
> 1. cluster with 4 DNs
> 2. the size of the file to be written is a little more than one block
> 3. write the first block to 3 DNs, DN1->DN2->DN3
> 4. all the data packets of first block is successfully acked and the client
> sets the pipeline stage to PIPELINE_CLOSE, but the last packet isn't sent out
> 5. DN2 and DN3 are down
> 6. client recovers the pipeline, but no new DN is added to the pipeline
> because of the current pipeline stage is PIPELINE_CLOSE
> 7. client continuously writes the last block, and try to close the file after
> written all the data
> 8. NN finds that the penultimate block doesn't has enough replica(our
> dfs.namenode.replication.min=2), and the client's close runs into indefinite
> loop(HDFS-2936), and at the same time, NN makes the last block's state to
> COMPLETE
> 9. shutdown the client
> 10. the file's lease exceeds hard limit
> 11. LeaseManager realizes that and begin to do lease recovery by call
> fsnamesystem.internalReleaseLease()
> 12. but the last block's state is COMPLETE, and this triggers lease manager's
> infinite loop and prints massive logs like this:
> {noformat}
> 2013-06-05,17:42:25,695 INFO
> org.apache.hadoop.hdfs.server.namenode.LeaseManager: Lease [Lease. Holder:
> DFSClient_NONMAPREDUCE_-1252656407_1, pendingcreates: 1] has expired hard
> limit
> 2013-06-05,17:42:25,695 INFO
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Recovering lease=[Lease.
> Holder: DFSClient_NONMAPREDUCE_-1252656407_1, pendingcreates: 1], src=
> /user/h_wuzesheng/test.dat
> 2013-06-05,17:42:25,695 WARN org.apache.hadoop.hdfs.StateChange: DIR*
> NameSystem.internalReleaseLease: File = /user/h_wuzesheng/test.dat, block
> blk_-7028017402720175688_1202597,
> lastBLockState=COMPLETE
> 2013-06-05,17:42:25,695 INFO
> org.apache.hadoop.hdfs.server.namenode.LeaseManager: Started block recovery
> for file /user/h_wuzesheng/test.dat lease [Lease. Holder: DFSClient_NONM
> APREDUCE_-1252656407_1, pendingcreates: 1]
> {noformat}
> (the 3rd line log is a debug log added by us)
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