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https://issues.apache.org/jira/browse/HADOOP-13028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15281459#comment-15281459
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Steve Loughran commented on HADOOP-13028:
-----------------------------------------
Actually this has thrown up something more fundamental: we do need an explicit
compatibility guideline & style rule about toString, something like
# toString: no guarantees. They are for logging and diagostics for people, not
for parsing by machines. They may also nest toString values of contained
objects, from hadoop and other libraries, neither of which contain any
guarantees either.
# code which generates command line output for machine parsing MUST NOT use the
toString() value to generate output which is then expected to be stable.
# A specific method, such as {{toStringStable()}} must be used to generate the
strings in such a situation, ideally with a regression test.
This is something to bring up on the dev list, as it is something we
essentially missed. [~cmccabe]: would you care for the honour?
> add low level counter metrics for S3A; use in read performance tests
> --------------------------------------------------------------------
>
> Key: HADOOP-13028
> URL: https://issues.apache.org/jira/browse/HADOOP-13028
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3, metrics
> Affects Versions: 2.8.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Attachments: HADOOP-13028-001.patch, HADOOP-13028-002.patch,
> HADOOP-13028-004.patch, HADOOP-13028-005.patch, HADOOP-13028-006.patch,
> HADOOP-13028-007.patch, HADOOP-13028-008.patch, HADOOP-13028-009.patch,
> HADOOP-13028-branch-2-008.patch, HADOOP-13028-branch-2-009.patch,
> HADOOP-13028-branch-2-010.patch, HADOOP-13028-branch-2-011.patch,
> HADOOP-13028-branch-2-012.patch,
> org.apache.hadoop.fs.s3a.scale.TestS3AInputStreamPerformance-output.txt,
> org.apache.hadoop.fs.s3a.scale.TestS3AInputStreamPerformance-output.txt
>
>
> against S3 (and other object stores), opening connections can be expensive,
> closing connections may be expensive (a sign of a regression).
> S3A FS and individual input streams should have counters of the # of
> open/close/failure+reconnect operations, timers of how long things take. This
> can be used downstream to measure efficiency of the code (how often
> connections are being made), connection reliability, etc.
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