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https://issues.apache.org/jira/browse/HDFS-6982?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Maysam Yabandeh updated HDFS-6982:
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Attachment: HDFS-6982.patch
I am attaching the first patch that imports the main components from our
standalone nntop tool to hdfs repo. The patch is not complete but I am
attaching it to get the preliminary feedbacks, e.g., whether we can move
forward with a single patch or we need to divide it into multiple patches, etc.
A couple of things missing in the patch:
# I removed the simple web page that shows the top users since it was written
using org.apache.hadoop.yarn.webapp. I am thinking that we probably need to
write a whole new page that does not depend on yarn. I am not sure at this
point which technology is recommended for that and to which page nntop results
could be added. I am wondering perhaps we can postpone this to another patch,
which would also make this patch simpler.
# The code for registering TopMetrics to metrics system is not present in the
patch as I was not sure where is the best place to put it.
# A user appearing in the current top list might not be present in the next
generated top list. The previously reported users should then be removed from
the exported jmx metrics. This desired behavior is not achieved with the
current implementation of MetricsSourceAdapter which resets its cache only if a
new metrics is added:
{code}
int oldCacheSize = attrCache.size();
int newCacheSize = updateAttrCache();
if (oldCacheSize < newCacheSize) {
updateInfoCache();
}
{code}
In our tool we had changed this behavior to always invoke updateInfoCache. I
did not import this change in the patch since I was not sure this change is
desirable for all use cases. I guess we can work on another patch that makes
this optional in MetricsSourceAdapter?
Comments are highly appreciated.
> nntop: top-like tool for name node users
> -----------------------------------------
>
> Key: HDFS-6982
> URL: https://issues.apache.org/jira/browse/HDFS-6982
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Maysam Yabandeh
> Attachments: HDFS-6982.patch, nntop-design-v1.pdf
>
>
> In this jira we motivate the need for nntop, a tool that, similarly to what
> top does in Linux, gives the list of top users of the HDFS name node and
> gives insight about which users are sending majority of each traffic type to
> the name node. This information turns out to be the most critical when the
> name node is under pressure and the HDFS admin needs to know which user is
> hammering the name node and with what kind of requests. Here we present the
> design of nntop which has been in production at Twitter in the past 10
> months. nntop proved to have low cpu overhead (< 2% in a cluster of 4K
> nodes), low memory footprint (less than a few MB), and quite efficient for
> the write path (only two hash lookup for updating a metric).
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