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https://issues.apache.org/jira/browse/BEAM-9434?focusedWorklogId=400245&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-400245
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ASF GitHub Bot logged work on BEAM-9434:
----------------------------------------
Author: ASF GitHub Bot
Created on: 09/Mar/20 17:30
Start Date: 09/Mar/20 17:30
Worklog Time Spent: 10m
Work Description: lukecwik commented on issue #11037: [BEAM-9434]
performance improvements reading many Avro files in S3
URL: https://github.com/apache/beam/pull/11037#issuecomment-596669808
I understand what your saying and how your solution resolves the problem.
I'm trying to say that the problem shouldn't occur in the first place
because
[AvroIO.read](https://github.com/apache/beam/blob/a4ab76881d843a17906d866f0d6225def82ea6d0/sdks/java/core/src/main/java/org/apache/beam/sdk/io/AvroIO.java#L1030)
should expand to
[MatchAll](https://github.com/apache/beam/blob/060d0874e0c831a71ca6b240c66c04d367c8793d/sdks/java/core/src/main/java/org/apache/beam/sdk/io/FileIO.java#L622)
that contains a
[Reshuffle](https://github.com/apache/beam/blob/060d0874e0c831a71ca6b240c66c04d367c8793d/sdks/java/core/src/main/java/org/apache/beam/sdk/io/FileIO.java#L641)
followed by
[ReadMatches](https://github.com/apache/beam/blob/060d0874e0c831a71ca6b240c66c04d367c8793d/sdks/java/core/src/main/java/org/apache/beam/sdk/io/FileIO.java#L690)
Reshuffle should ensure that there is a repartition between MatchAll and
ReadMatches, is it missing (it is difficult to tell from your screenshots)? If
it isn't missing, they why is the following stage only executing on a single
machine (since repartition shouldn't be restricting output to only a single
machine)?
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Issue Time Tracking
-------------------
Worklog Id: (was: 400245)
Time Spent: 2h 20m (was: 2h 10m)
> Performance improvements processing a large number of Avro files in S3+Spark
> ----------------------------------------------------------------------------
>
> Key: BEAM-9434
> URL: https://issues.apache.org/jira/browse/BEAM-9434
> Project: Beam
> Issue Type: Improvement
> Components: io-java-aws, sdk-java-core
> Affects Versions: 2.19.0
> Reporter: Emiliano Capoccia
> Assignee: Emiliano Capoccia
> Priority: Minor
> Time Spent: 2h 20m
> Remaining Estimate: 0h
>
> There is a performance issue when processing a large number of small Avro
> files in Spark on K8S (tens of thousands or more).
> The recommended way of reading a pattern of Avro files in Beam is by means of:
>
> {code:java}
> PCollection<AvroGenClass> records = p.apply(AvroIO.read(AvroGenClass.class)
> .from("s3://my-bucket/path-to/*.avro").withHintMatchesManyFiles())
> {code}
> However, in the case of many small files, the above results in the entire
> reading taking place in a single task/node, which is considerably slow and
> has scalability issues.
> The option of omitting the hint is not viable, as it results in too many
> tasks being spawn, and the cluster being busy doing coordination of tiny
> tasks with high overhead.
> There are a few workarounds on the internet which mainly revolve around
> compacting the input files before processing, so that a reduced number of
> bulky files is processed in parallel.
>
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