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https://issues.apache.org/jira/browse/HDFS-8873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14804503#comment-14804503
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Colin Patrick McCabe commented on HDFS-8873:
--------------------------------------------
The jenkins errors look like:
{code}
java.lang.NoSuchMethodError:
org.apache.hadoop.hdfs.protocol.DatanodeInfo.<init>(Lorg/apache/hadoop/hdfs/protocol/DatanodeID;Ljava/lang/String;JJJJJJJJILorg/apache/hadoop/hdfs/protocol/DatanodeInfo$AdminStates;)V
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:591)
{code}
We've seen this before and never managed to track it down. It seems to be a
bug in our Jenkins integration, possibly related to having multiple maven
invocations going on at once sharing the same .m2 directory. I will re-trigger
the build.
bq. The whitespace error is interesting. I changed line n in the patch. Jenkins
complained about the whitespace on line n+1. I fixed the whitespace on line n+1
in the next patch. Jenkins is now complaining about the whitespace on line n+2
I would say just leave it alone. If you didn't introduce the whitespace issue
then don't worry about it. We really should turn off most of those checkstyle
things since it provides no value.
> throttle directoryScanner
> -------------------------
>
> Key: HDFS-8873
> URL: https://issues.apache.org/jira/browse/HDFS-8873
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Affects Versions: 2.7.1
> Reporter: Nathan Roberts
> Assignee: Daniel Templeton
> Attachments: HDFS-8873.001.patch, HDFS-8873.002.patch,
> HDFS-8873.003.patch
>
>
> The new 2-level directory layout can make directory scans expensive in terms
> of disk seeks (see HDFS-8791) for details.
> It would be good if the directoryScanner() had a configurable duty cycle that
> would reduce its impact on disk performance (much like the approach in
> HDFS-8617).
> Without such a throttle, disks can go 100% busy for many minutes at a time
> (assuming the common case of all inodes in cache but no directory blocks
> cached, 64K seeks are required for full directory listing which translates to
> 655 seconds)
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