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https://issues.apache.org/jira/browse/HDFS-17216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17833023#comment-17833023
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ASF GitHub Bot commented on HDFS-17216:
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xiaojunxiang2023 commented on PR #6138:
URL: https://github.com/apache/hadoop/pull/6138#issuecomment-2031158756
> just missed this as it went in under hdfs/distcp rather than hadoop common
distcp (why two? who knows?)
>
> made some basic comments. If you can address them as a followup (same jira
id, mention me in the PR) then we can get this in and then into branch-3.4.
>
> please don't backport until then!
Hi~, I double-checked that distcp only exists in hadoop-tools/hadop-distcp,
not hadoop-common, right?
> When distcp handle the small files, the bandwidth parameter will be invalid,
> resulting in serious overspeed behavior
> --------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-17216
> URL: https://issues.apache.org/jira/browse/HDFS-17216
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: distcp
> Affects Versions: 3.3.4
> Reporter: xiaojunxiang
> Assignee: xiaojunxiang
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.5.0
>
> Attachments: DiscpAnalyze.jpg
>
>
> When distcp copies small files (file size slightly smaller than the
> bandwidth), the throbber only starts to throb after 1 second, and the
> throttled is specific to a single file. so the throbber becomes invalid,
> causing distcp to fill the cluster bandwidth and crush production traffic,
> which is a terrible thing.
> Also, it takes time for files to set up the IO pipeline, so you shouldn't
> test with very small files, which will slow the transfer, especially as
> bandwidth kicks in, which will amplify the impact of small files on the rate
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