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Posted to issues@ozone.apache.org by "runzhiwang (Jira)" <ji...@apache.org> on 2020/04/17 04:03:00 UTC
[jira] [Updated] (HDDS-3223) Read a big object is too slow by s3g
[ https://issues.apache.org/jira/browse/HDDS-3223?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
runzhiwang updated HDDS-3223:
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Summary: Read a big object is too slow by s3g (was: Read a big object is slower than write it by s3g)
> Read a big object is too slow by s3g
> ------------------------------------
>
> Key: HDDS-3223
> URL: https://issues.apache.org/jira/browse/HDDS-3223
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Reporter: runzhiwang
> Assignee: runzhiwang
> Priority: Major
> Attachments: screenshot-1.png
>
>
> *What's the problem ?*
> Read a 300M file, it cost about 25 seconds, i.e. 12.8M/s, which is too slow. Then I capture the packet. You can see from the image, read a 300M file need 10 GET requests, each GET request read about 32M.
> The first GET request cost about 1 second, but the 10th GET request cost about 23 seconds.
> !screenshot-1.png!
> *What's the reason ?*
> When do GET, the stack is: [IOUtils::copyLarge|https://github.com/apache/hadoop-ozone/blob/master/hadoop-ozone/s3gateway/src/main/java/org/apache/hadoop/ozone/s3/endpoint/ObjectEndpoint.java#L262] -> [IOUtils::skipFully|https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/IOUtils.java#L1190] -> [IOUtils::skip|https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/IOUtils.java#L2064] -> [InputStream::read|https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/IOUtils.java#L1957].
> It means, the 10th GET request which should read 270M-300M, but to skip 0-270M, it also [InputStream::read|https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/IOUtils.java#L1957] 0-270M. So the GET request become slower and slower
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