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Renkai Ge commented on FLINK-4883: ---------------------------------- How about to extend the method org.apache.flink.streaming.api.datastream.DataStream#clean to make it not only clean the function but also check if the function is a scala object, I think it's the way to implement the detection with minimal changes. > Prevent UDFs implementations through Scala singleton objects > ------------------------------------------------------------ > > Key: FLINK-4883 > URL: https://issues.apache.org/jira/browse/FLINK-4883 > Project: Flink > Issue Type: Bug > Reporter: Stefan Richter > Assignee: Renkai Ge > > Currently, user can create and use UDFs in Scala like this: > {code} > object FlatMapper extends RichCoFlatMapFunction[Long, String, (Long, String)] > { > ... > } > {code} > However, this leads to problems as the UDF is now a singleton that Flink > could use across several operator instances, which leads to job failures. We > should detect and prevent the usage of singleton UDFs. -- This message was sent by Atlassian JIRA (v6.3.4#6332)