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From "Li Lu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-3901) Populate flow run data in the flow_run & flow activity tables
Date Tue, 15 Sep 2015 21:21:47 GMT

    [ https://issues.apache.org/jira/browse/YARN-3901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14746239#comment-14746239
] 

Li Lu commented on YARN-3901:
-----------------------------

Hi [~vrushalic], thanks for the work! I feel the current patch is much closer. Some of my
review comments:

- Column.java
Let's make it clear in the comments if attributes can be null. (I believe it can be null but
let's make it explicit. )

- TimelineWriterUtils.java
Quick question: when checking application finish event and its timestamp, we only search for
the very last event event. Will there be some corner cases where the application finish event
is not the last one? Such as, another event accidentally has the same timestamp as the finish
event? I'm not sure if we have any strong guarantee on this (so that the chance is low). 

- TimestampGenerator.java
The lock-free algorithm to generate (locally-) unique timestamps looks good to me. Depend
on the usage maybe we'd like to promote this algorithm to a more common place if other part
of the code needs it as well. Any special considerations on not directly using getAndAdd (fetch-and-increment)
here? 

- TimelineWriterUtils.java
TimelineWriterUtils#getTagFromAttribute is much better than the previous versions. It may
be better to let the key of attribute entry to identify its own type? Right now we're requiring
AggregationOperations and AggregationCompactionDimension to have disjoint enum values. This
implicit requirement may be error pruning: if two attributes accidentally have DEFAULT, we're
confusing them. Not sure if this is the top priority for now but we may need to fix it sometime
later. 

- FlowScanner.java
Unify findMaxCell and findMinCell? 
I'm a little bit confused on SUM and SUM_FINAL: what's the difference (we treat them in the
same way in collectCells)? 
Right now we treat all metric values to be Long. Let's decide that later. 

- FlowRunTable.java
We're mixing real "info" with metrics (info.m!xxxxx) together in the info column family. I
think this is worth noting somewhere? 

- TestHBaseStorageFlowRunFlowActivity.java
Split into test flowRun and test flowActivity? Although added in the same JIRA, the function
of the flowRun table and flowActivity tables are different (online aggregation and real-time
activity info). 
It's fine to directly read data out in the UT now. We may want to switch this to use readers
sometime later?
Do we need to test single data aggregation? The two {{getEntityMetricsApp}} methods only generates
time series metrics. 
checkFlowRunTable(), shall we have some better ways to check the values 141 and 57? Say, is
it possible to check them dynamically rather than hard code them? 

- With regard to FlowActivityTable, maybe I'm still missing some points here, but how do we
maintain the active flow list for the past 24 hrs? I noticed we never remove or disable anything
in this table, so do we do this by setting the ttl of the table? Or we create different rows
for the same application to differentiate the day an entity was posted? I think we're using
the latter but would like to confirm. Also, with the current design, when the reader tries
to get latest activities on a cluster, it can craft a row key prefix {{cluster!inv(currTime-24h)}}
and scan from the very beginning to this record, right? (I'm trying to connect the two pieces
together. )

> Populate flow run data in the flow_run & flow activity tables
> -------------------------------------------------------------
>
>                 Key: YARN-3901
>                 URL: https://issues.apache.org/jira/browse/YARN-3901
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelineserver
>            Reporter: Vrushali C
>            Assignee: Vrushali C
>         Attachments: YARN-3901-YARN-2928.1.patch, YARN-3901-YARN-2928.2.patch, YARN-3901-YARN-2928.3.patch,
YARN-3901-YARN-2928.4.patch, YARN-3901-YARN-2928.5.patch, YARN-3901-YARN-2928.6.patch, YARN-3901-YARN-2928.7.patch,
YARN-3901-YARN-2928.8.patch
>
>
> As per the schema proposed in YARN-3815 in https://issues.apache.org/jira/secure/attachment/12743391/hbase-schema-proposal-for-aggregation.pdf
> filing jira to track creation and population of data in the flow run table. 
> Some points that are being  considered:
> - Stores per flow run information aggregated across applications, flow version
> RM’s collector writes to on app creation and app completion
> - Per App collector writes to it for metric updates at a slower frequency than the metric
updates to application table
> primary key: cluster ! user ! flow ! flow run id
> - Only the latest version of flow-level aggregated metrics will be kept, even if the
entity and application level keep a timeseries.
> - The running_apps column will be incremented on app creation, and decremented on app
completion.
> - For min_start_time the RM writer will simply write a value with the tag for the applicationId.
A coprocessor will return the min value of all written values. - 
> - Upon flush and compactions, the min value between all the cells of this column will
be written to the cell without any tag (empty tag) and all the other cells will be discarded.
> - Ditto for the max_end_time, but then the max will be kept.
> - Tags are represented as #type:value. The type can be not set (0), or can indicate running
(1) or complete (2). In those cases (for metrics) only complete app metrics are collapsed
on compaction.
> - The m! values are aggregated (summed) upon read. Only when applications are completed
(indicated by tag type 2) can the values be collapsed.
> - The application ids that have completed and been aggregated into the flow numbers are
retained in a separate column for historical tracking: we don’t want to re-aggregate for
those upon replay
> 



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