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From "Weiwei Yang (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HDFS-12443) Ozone: Improve SCM block deletion throttling algorithm
Date Mon, 30 Oct 2017 13:06:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-12443?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16224885#comment-16224885
] 

Weiwei Yang edited comment on HDFS-12443 at 10/30/17 1:05 PM:
--------------------------------------------------------------

Hi [~linyiqun]

Please take a look at the pdf I just uploaded [HDFS-12443-SCM-blockdeletion-throttle.pdf|https://issues.apache.org/jira/secure/attachment/12894736/HDFS-12443-SCM-blockdeletion-throttle.pdf],
the key issue here is we want to properly throttle the size of message sent to DN, see chart
page 1 {{CommandQueue}}. In every interval, we want each DN gets a throttled number of {{DeletedBlocksCommand}}
to process. But delLog has no notion of DN, so it's a bit difficult to get there. Please let
me know your thought, thanks.


was (Author: cheersyang):
Hi [~linyiqun]

Please take a look at the pdf I just uploaded ^HDFS-12443-SCM-blockdeletion-throttle.pdf,
the key issue here is we want to properly throttle the size of message sent to DN, see chart
page 1 {{CommandQueue}}. In every interval, we want each DN gets a throttled number of {{DeletedBlocksCommand}}
to process. But delLog has no notion of DN, so it's a bit difficult to get there. Please let
me know your thought, thanks.

> Ozone: Improve SCM block deletion throttling algorithm 
> -------------------------------------------------------
>
>                 Key: HDFS-12443
>                 URL: https://issues.apache.org/jira/browse/HDFS-12443
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: ozone, scm
>            Reporter: Weiwei Yang
>            Assignee: Yiqun Lin
>              Labels: OzonePostMerge
>         Attachments: HDFS-12443-HDFS-7240.001.patch, HDFS-12443-HDFS-7240.002.patch,
HDFS-12443-HDFS-7240.002.patch, HDFS-12443-SCM-blockdeletion-throttle.pdf
>
>
> Currently SCM scans delLog to send deletion transactions to datanode periodically, the
throttling algorithm is simple, it scans at most {{BLOCK_DELETE_TX_PER_REQUEST_LIMIT}} (by
default 50) at a time. This is non-optimal, worst case it might cache 50 TXs for 50 different
DNs so each DN will only get 1 TX to proceed in an interval, this will make the deletion slow.
An improvement to this is to make this throttling by datanode, e.g 50 TXs per datanode per
interval.



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