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https://issues.apache.org/jira/browse/FLINK-1319?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14569202#comment-14569202
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ASF GitHub Bot commented on FLINK-1319:
---------------------------------------
Github user uce commented on a diff in the pull request:
https://github.com/apache/flink/pull/729#discussion_r31530742
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/operators/SingleInputUdfOperator.java
---
@@ -54,8 +54,11 @@
private Map<String, DataSet<?>> broadcastVariables;
+ // NOTE: only set this variable via setSemanticProperties()
--- End diff --
I think this refactoring is quite fragile. The semantic properties utility
is not returning an empty properties object, but null and you take care of
setting it correctly here depending on whether the forwarded fields have been
set manually or not.
If optimize is enabled and there are manual annotations, they will be
overriden. I am wondering if it is better to have manual annotations trump
optimizer annotations. What's your opinion on this?
> Add static code analysis for UDFs
> ---------------------------------
>
> Key: FLINK-1319
> URL: https://issues.apache.org/jira/browse/FLINK-1319
> Project: Flink
> Issue Type: New Feature
> Components: Java API, Scala API
> Reporter: Stephan Ewen
> Assignee: Timo Walther
> Priority: Minor
>
> Flink's Optimizer takes information that tells it for UDFs which fields of
> the input elements are accessed, modified, or frwarded/copied. This
> information frequently helps to reuse partitionings, sorts, etc. It may speed
> up programs significantly, as it can frequently eliminate sorts and shuffles,
> which are costly.
> Right now, users can add lightweight annotations to UDFs to provide this
> information (such as adding {{@ConstandFields("0->3, 1, 2->1")}}.
> We worked with static code analysis of UDFs before, to determine this
> information automatically. This is an incredible feature, as it "magically"
> makes programs faster.
> For record-at-a-time operations (Map, Reduce, FlatMap, Join, Cross), this
> works surprisingly well in many cases. We used the "Soot" toolkit for the
> static code analysis. Unfortunately, Soot is LGPL licensed and thus we did
> not include any of the code so far.
> I propose to add this functionality to Flink, in the form of a drop-in
> addition, to work around the LGPL incompatibility with ALS 2.0. Users could
> simply download a special "flink-code-analysis.jar" and drop it into the
> "lib" folder to enable this functionality. We may even add a script to
> "tools" that downloads that library automatically into the lib folder. This
> should be legally fine, since we do not redistribute LGPL code and only
> dynamically link it (the incompatibility with ASL 2.0 is mainly in the
> patentability, if I remember correctly).
> Prior work on this has been done by [~aljoscha] and [~skunert], which could
> provide a code base to start with.
> *Appendix*
> Hompage to Soot static analysis toolkit: http://www.sable.mcgill.ca/soot/
> Papers on static analysis and for optimization:
> http://stratosphere.eu/assets/papers/EnablingOperatorReorderingSCA_12.pdf and
> http://stratosphere.eu/assets/papers/openingTheBlackBoxes_12.pdf
> Quick introduction to the Optimizer:
> http://stratosphere.eu/assets/papers/2014-VLDBJ_Stratosphere_Overview.pdf
> (Section 6)
> Optimizer for Iterations:
> http://stratosphere.eu/assets/papers/spinningFastIterativeDataFlows_12.pdf
> (Sections 4.3 and 5.3)
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