Illegal reflective access by org.apache.flink.api.java.ClosureCleaner

Question

When I run a SocketWindowWordCount Program in Apache flink, it shows a

WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner

WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by org.apache.flink.api.java.ClosureCleaner (file:/home/aman.srivastava/Downloads/flink-1.10.0/lib/flink-dist_2.11-1.10.0.jar) to field java.lang.String.value WARNING: Please consider reporting this to the maintainers of org.apache.flink.api.java.ClosureCleaner WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release Job has been submitted with JobID a4badaa76080e47e82a322a4e2060e45

Answer 1

This warning is because you probably use Java 11. Flink docs says:

These warnings are considered harmless and will be addressed in future Flink releases.

You can find more here: https://ci.apache.org/projects/flink/flink-docs-stable/release-notes/flink-1.10.html#java-11-support-flink-10725