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https://issues.apache.org/jira/browse/FLINK-24279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17414930#comment-17414930
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Dawid Wysakowicz commented on FLINK-24279:
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I see. Just a note that if you need to change the DataStream API you will need
a FLIP for it.
> Support withBroadcast in DataStream
> -----------------------------------
>
> Key: FLINK-24279
> URL: https://issues.apache.org/jira/browse/FLINK-24279
> Project: Flink
> Issue Type: New Feature
> Components: Library / Machine Learning
> Reporter: Zhipeng Zhang
> Priority: Major
>
> When doing machine learning using DataStream, we found that DataStream lacks
> withBroadcast() function, which could be useful in machine learning.
>
> A DataSet-based demo is like:
> {code:java}
> DataSet<?> d1 = ...;
> DataSet<?> d2 = ...;
> d1.map(new RichMapFunction <?, ?>() {
> @Override
> public Object map(Object aLong) throws Exception{
> List<?> elements = getRuntimeContext().getBroadcastVariable("d2");
> ...;
> }
> }).withBroadcastSet(d2, "d2");
> {code}
>
> The withBroadcast() function incurs priority-base data-consuming. For example
> in the above code snippet, we cannot consume any element from d1 before we
> consumed all of elements in d2.
>
> Thus when supporting withBroadcast() in DataStream, we also need
> priority-base data-consuming. This could probably lead to deadlock and
> DataStream does not provide a solution for deadlock.
>
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