[
https://issues.apache.org/jira/browse/HDFS-5693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13977434#comment-13977434
]
Jing Zhao commented on HDFS-5693:
---------------------------------
Thanks for working on this, [~mingma]! The patch looks pretty good to me. Some
nits:
# It may be better to put the quick check in listCorruptFileBlocks into a
separate method, considering the original method is already long. But since you
also plan to file a separate jira to for listCorruptFileBlocks, maybe we can
move this part of change there.
# A space is missing for the following comment:
{code}
+ //There is no need to take fSNamesystem's lock as
+ // FSDirectory has its own lock.
{code}
# It will be better to have some javadoc for MBeanClient.
> Few NN metrics data points were collected via JMX when NN is under heavy load
> -----------------------------------------------------------------------------
>
> Key: HDFS-5693
> URL: https://issues.apache.org/jira/browse/HDFS-5693
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Ming Ma
> Assignee: Ming Ma
> Attachments: HADOOP-5693.patch, HDFS-5693.patch
>
>
> JMX sometimes doesn’t return any value when NN is under heavy load. However,
> that is when we would like to get metrics to help to diagnosis the issue.
> When NN is under heavy load due to bad application or other reasons, it holds
> FSNamesystem's writer lock for a long period of time. Many of the
> FSNamesystem metrics require FSNamesystem's reader lock and thus can't be
> processed.
> This is a special case to improve the overall NN concurrency.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
