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https://issues.apache.org/jira/browse/HDFS-10301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15380310#comment-15380310
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Konstantin Shvachko commented on HDFS-10301:
--------------------------------------------
Reviewed latest patch. Got a few nits:
# In {{BlockManager.removeZombieStorages()}} you should add a check {{if(node
== null)}}. The node could have been deleted while we were not holding
{{writeLock}}.
# {{DatanodeDescriptor.removeZombieStorages()}} methods does not need to be
public. Should be package private.
# Remove empty line change in {{BPServiceActor.blockReport()}}.
Also the comment here is confusing. You might want to clarify it.
# checkstyle warning tells that either {{STORAGE_REPORT}} should be declared
{{final}} or it should not be all-capital. I think {{final}} makes sense.
Also I think that [~cmccabe]'s veto, formulated as
??I am -1 on a patch which adds extra RPCs.??
is fully addressed now. The storage report was added to the last RPC
representing a single block report. The last patch does not add extra RPCs.
So I plan to commit this three days from today. Given of course the nits above
are fixed.
> BlockReport retransmissions may lead to storages falsely being declared
> zombie if storage report processing happens out of order
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-10301
> URL: https://issues.apache.org/jira/browse/HDFS-10301
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.6.1
> Reporter: Konstantin Shvachko
> Assignee: Vinitha Reddy Gankidi
> Priority: Critical
> Attachments: HDFS-10301.002.patch, HDFS-10301.003.patch,
> HDFS-10301.004.patch, HDFS-10301.005.patch, HDFS-10301.006.patch,
> HDFS-10301.007.patch, HDFS-10301.008.patch, HDFS-10301.01.patch,
> HDFS-10301.sample.patch, zombieStorageLogs.rtf
>
>
> When NameNode is busy a DataNode can timeout sending a block report. Then it
> sends the block report again. Then NameNode while process these two reports
> at the same time can interleave processing storages from different reports.
> This screws up the blockReportId field, which makes NameNode think that some
> storages are zombie. Replicas from zombie storages are immediately removed,
> causing missing blocks.
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