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https://issues.apache.org/jira/browse/YARN-5739?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15694139#comment-15694139
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Varun Saxena commented on YARN-5739:
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I was wondering if we can refactor this code. As I said when I first reviewed
this JIRA, EntityTypeReader being a subclass of GenericEntityReader does not
seem correct. Infact is it even fit to be a subclass of TimelineEntityReader ?
We are not attempting to return timeline entities here however it can be said
in backend we store a timeline entity only.
Basically because we are deriving EntityTypeReader from TimelineEntityReader we
have to override readEntities and create the response as a set of
TimelineEntity objects unnecessarily even though what we just need is a list of
entity types. I just find this part a little weird.
Looking at the code, the main thing which we need from GenericEntityReader is
the part about looking up flow context. Rest of the required code is very
small. Should we pull out the code related to AppToFlowTable querying (i.e.
looking up flow context) and move it to a separate class ?
We can then have EntityTypeReader as a standalone class with both it and
GenericEntityReader referring to another class to look up flow context.
I do not think when it comes to querying entity types, even the filters or
timeline data to retrieve stored in TimelineEntityReader will be useful.
The best I can think of supporting as a filter for this query is that we may
want to return entity types starting with a certain prefix.
Thoughts ?
> Provide timeline reader API to list available timeline entity types for one
> application
> ---------------------------------------------------------------------------------------
>
> Key: YARN-5739
> URL: https://issues.apache.org/jira/browse/YARN-5739
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: timelinereader
> Reporter: Li Lu
> Assignee: Li Lu
> Attachments: YARN-5739-YARN-5355.001.patch,
> YARN-5739-YARN-5355.002.patch, YARN-5739-YARN-5355.003.patch,
> YARN-5739-YARN-5355.004.patch
>
>
> Right now we only show a part of available timeline entity data in the new
> YARN UI. However, some data (especially library specific data) are not
> possible to be queried out by the web UI. It will be appealing for the UI to
> provide an "entity browser" for each YARN application. Actually, simply
> dumping out available timeline entities (with proper pagination, of course)
> would be pretty helpful for UI users.
> On timeline side, we're not far away from this goal. Right now I believe the
> only thing missing is to list all available entity types within one
> application. The challenge here is that we're not storing this data for each
> application, but given this kind of call is relatively rare (compare to
> writes and updates) we can perform some scanning during the read time.
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