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https://issues.apache.org/jira/browse/HDFS-16521?focusedWorklogId=762739&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-762739
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ASF GitHub Bot logged work on HDFS-16521:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 27/Apr/22 06:44
Start Date: 27/Apr/22 06:44
Worklog Time Spent: 10m
Work Description: hadoop-yetus commented on PR #4107:
URL: https://github.com/apache/hadoop/pull/4107#issuecomment-1110606241
:broken_heart: **-1 overall**
| Vote | Subsystem | Runtime | Logfile | Comment |
|:----:|----------:|--------:|:--------:|:-------:|
| +0 :ok: | reexec | 0m 0s | | Docker mode activated. |
| -1 :x: | patch | 0m 27s | |
https://github.com/apache/hadoop/pull/4107 does not apply to trunk. Rebase
required? Wrong Branch? See
https://cwiki.apache.org/confluence/display/HADOOP/How+To+Contribute for help.
|
| Subsystem | Report/Notes |
|----------:|:-------------|
| GITHUB PR | https://github.com/apache/hadoop/pull/4107 |
| Console output |
https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4107/7/console |
| versions | git=2.17.1 |
| Powered by | Apache Yetus 0.14.0-SNAPSHOT https://yetus.apache.org |
This message was automatically generated.
Issue Time Tracking
-------------------
Worklog Id: (was: 762739)
Time Spent: 3h 50m (was: 3h 40m)
> DFS API to retrieve slow datanodes
> ----------------------------------
>
> Key: HDFS-16521
> URL: https://issues.apache.org/jira/browse/HDFS-16521
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Major
> Labels: pull-request-available
> Time Spent: 3h 50m
> Remaining Estimate: 0h
>
> Providing DFS API to retrieve slow nodes would help add an additional option
> to "dfsadmin -report" that lists slow datanodes info for operators to take a
> look, specifically useful filter for larger clusters.
> The other purpose of such API is for HDFS downstreamers without direct access
> to namenode http port (only rpc port accessible) to retrieve slownodes.
> Moreover,
> [FanOutOneBlockAsyncDFSOutput|https://github.com/apache/hbase/blob/master/hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutput.java]
> in HBase currently has to rely on it's own way of marking and excluding slow
> nodes while 1) creating pipelines and 2) handling ack, based on factors like
> the data length of the packet, processing time with last ack timestamp,
> whether flush to replicas is finished etc. If it can utilize slownode API
> from HDFS to exclude nodes appropriately while writing block, a lot of it's
> own post-ack computation of slow nodes can be _saved_ or _improved_ or based
> on further experiment, we could find _better solution_ to manage slow node
> detection logic both in HDFS and HBase. However, in order to collect more
> data points and run more POC around this area, HDFS should provide API for
> downstreamers to efficiently utilize slownode info for such critical
> low-latency use-case (like writing WALs).
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