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https://issues.apache.org/jira/browse/HADOOP-15124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16300770#comment-16300770
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Igor Dvorzhak edited comment on HADOOP-15124 at 12/22/17 2:30 AM:
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I have added a draft implementation of a property that disables per-thread
statistics to the PR.
Here is performance profiling results ({{Statistics}} code paths) of the latest
changes:
|| || || ||TeraGen 1TB|| || || ||
|| || ||GCS|| || ||HDFS|| ||
| |No changes|LongAdder + Per-Thread|LongAdder|No changes|LongAdder +
Per-Thread|LongAdder|
|CPU, ms|1,430|1,880|3.86|805.85|349.64|172.6|
|CPU, %|23.4|28.4|0.057|10.9|4.61|2.29|
|Wall, ms|11,420|1,900|3.79|11,270|503.7|242.83|
|Wall, %|6.45|1.11|0.002|6.34|0.303|0.146|
Legend:
* "No changes" - stock Hadoop
* "LongAdder + Per-Thread" - FS.Statistics with LongAdder backend and with
per-thread statistic enabled
* "LongAdder" - FS.Statistics with LongAdder backend and with per-thread
statistic disabled
Performance profiling results summary: this change improves performance in all
tested cases except slight regression in CPU time for GCS with enabled
per-thread statistics.
While change is not complete yet (needs tests, javadocs and proper property
wiring), main functipnaity looks ready for review already.
What should I do to move this change forward? (I think it will be better to try
to get consensus on it, before investing more time into finishing it, in case
it will be rejected).
Also, I didn't figure out yet how to pass configuration/property value to
FileSystem.Statistics class. Maybe you can advise here?
was (Author: medb):
I have added a draft implementation of a property that disables per-thread
statistics to the PR.
Here is performance profiling results ({{Statistics}} code paths) of latest
changes:
|| || || ||TeraGen 1TB|| || || ||
|| || ||GCS|| || ||HDFS|| ||
| |No changes|LongAdder + Per-Thread|LongAdder|No changes|LongAdder +
Per-Thread|LongAdder|
|CPU, ms|1,430|1,880|3.86|805.85|349.64|172.6|
|CPU, %|23.4|28.4|0.057|10.9|4.61|2.29|
|Wall, ms|11,420|1,900|3.79|11,270|503.7|242.83|
|Wall, %|6.45|1.11|0.002|6.34|0.303|0.146|
Legend:
* "No changes" - stock Hadoop
* "LongAdder + Per-Thread" - FS.Statistics with LongAdder backend and with
per-thread statistic enabled
* "LongAdder" - FS.Statistics with LongAdder backend and with per-thread
statistic disabled
Performance profiling results summary: this change improves performance in all
tested cases except slight regression in CPU time for GCS with enabled
per-thread statistics.
While change is not complete yet (needs tests, javadocs and proper property
wiring), main functipnaity looks ready for review already.
What should I do to move this change forward? (I think it will be better to try
to get consensus on it, before investing more time into finishing it, in case
it will be rejected).
Also, I didn't figure out yet how to pass configuration/property value to
FileSystem.Statistics class. Maybe you can advise here?
> Slow FileSystem.Statistics counters implementation
> --------------------------------------------------
>
> Key: HADOOP-15124
> URL: https://issues.apache.org/jira/browse/HADOOP-15124
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: common
> Affects Versions: 2.9.0, 2.8.3, 2.7.5, 3.0.0
> Reporter: Igor Dvorzhak
> Assignee: Igor Dvorzhak
> Labels: common, filesystem, statistics
>
> While profiling 1TB TeraGen job on Hadoop 2.8.2 cluster (Google Dataproc, 2
> workers, GCS connector) I saw that FileSystem.Statistics code paths Wall time
> is 5.58% and CPU time is 26.5% of total execution time.
> After switching FileSystem.Statistics implementation to LongAdder, consumed
> Wall time decreased to 0.006% and CPU time to 0.104% of total execution time.
> Total job runtime decreased from 66 mins to 61 mins.
> These results are not conclusive, because I didn't benchmark multiple times
> to average results, but regardless of performance gains switching to
> LongAdder simplifies code and reduces its complexity.
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