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https://issues.apache.org/jira/browse/SPARK-44808?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wei Liu resolved SPARK-44808.
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Resolution: Won't Do
> refreshListener() API on StreamingQueryManager for spark connect
> ----------------------------------------------------------------
>
> Key: SPARK-44808
> URL: https://issues.apache.org/jira/browse/SPARK-44808
> Project: Spark
> Issue Type: New Feature
> Components: Connect, Structured Streaming
> Affects Versions: 4.0.0
> Reporter: Wei Liu
> Priority: Major
>
> I’m thinking of an improvement for connect python listener and foreachBatch.
> Currently if you define a variable outside of the function, you can’t
> actually see it on client side if it’s touched in the function because the
> operation is on server side, e.g.
>
>
> {code:java}
> x = 0
> class MyListener(StreamingQueryListener):
> def onQueryStarted(e):
> x = 100
> self.y = 200
> spark.streams.addListener(MyListener())
> q = spark.readStream.....start()
>
> # x is still 0, self.y is not defined
> {code}
>
>
> But for the self.y case, there could be an improvement.
>
> The server side is capable of pickle serialize the whole listener instance
> again, and send back to the client.
>
> So we could define a new interface on the streaming query manager, maybe
> called refreshListener(listener), e.g. use it as
> `spark.streams.refreshListener()`
>
>
> {code:java}
> def refreshListener(listener: StreamingQueryListener) ->
> StreamingQueryListener
> # send the listener id with this refresh request, server receives this
> request and serializes the listener again, and send back to client, so the
> returned new listener contains the updated value self.y
>
> {code}
>
> For `foreachBatch`, we could wrap the function to a new class
>
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