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https://issues.apache.org/jira/browse/FLINK-1319?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14574204#comment-14574204
 ] 

ASF GitHub Bot commented on FLINK-1319:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/729#discussion_r31799272
  
    --- Diff: 
flink-java/src/main/java/org/apache/flink/api/java/functions/SemanticPropUtil.java
 ---
    @@ -309,15 +308,20 @@ public static DualInputSemanticProperties 
getSemanticPropsDual(
                        getSemanticPropsDualFromString(result, forwardedFirst, 
forwardedSecond,
                                        nonForwardedFirst, nonForwardedSecond, 
readFirst, readSecond, inType1, inType2, outType);
                        return result;
    -           } else {
    -                   return new DualInputSemanticProperties();
                }
    +           return null;
    +   }
    +
    +   public static void 
getSemanticPropsSingleFromString(SingleInputSemanticProperties result,
    +                                                                           
                                String[] forwarded, String[] nonForwarded, 
String[] readSet,
    +                                                                           
                                TypeInformation<?> inType, TypeInformation<?> 
outType) {
    +           getSemanticPropsSingleFromString(result, forwarded, 
nonForwarded, readSet, inType, outType, false);
        }
     
        public static void 
getSemanticPropsSingleFromString(SingleInputSemanticProperties result,
                        String[] forwarded, String[] nonForwarded, String[] 
readSet,
    -                   TypeInformation<?> inType, TypeInformation<?> outType)
    -   {
    +                   TypeInformation<?> inType, TypeInformation<?> outType,
    +                   boolean skipIncompatibleTypes) {
    --- End diff --
    
    OK, got it. Thanks for explaining. :-) 


> 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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