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From Olga Golovneva <melcha...@gmail.com>
Subject On (FLINK-1526) JIRA issue
Date Wed, 21 Sep 2016 16:50:43 GMT
Hi devs,

I was working on  (FLINK-1526) "Add Minimum Spanning Tree library method
and example" issue. I've developed (Java) code that implements distributed
Boruvka's algorithm in Gelly library. I've run several tests and it seems
to work fine, although I didn't test it on extremely large input graphs
yet, and I'm also trying to optimize my code.
Particularly, I have two main issues:

1. Nested loops.
I have to use nested loops, and I do not see the way to avoid them. As they
are currently not supported, I'm using Bulk Iterations inside a "classic"
while loop. I've included in attachment simple example
MyNestedIterationExample that shows this issue.

2. For some reason I cannot create class that works with types with generic
variables in Tuple2(or Tuple3), thus my code does not support generic
types. I also included simple example MyTuple3Example. Here is the
Exception I get:
"Exception in thread "main"
org.apache.flink.api.common.functions.InvalidTypesException: Type of
TypeVariable 'EV' in 'class
org.apache.flink.graph.examples.MyTuple3Example$InitializeEdges' could not
be determined. This is most likely a type erasure problem. The type
extraction currently supports types with generic variables only in cases
where all variables in the return type can be deduced from the input

I would really appreciate if someone could explain me know how to avoid
this Exception. Otherwise, I could submit my code for testing.

Best regards,
Olga Golovneva

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