[jira] [Created] (FLINK-13451) Rework CommonTestUtils.createClassNotInClassPath() to not use Unsafe.defineClass()

[Shang Yuanchun (Jira)]

Stephan Ewen created FLINK-13451:
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             Summary: Rework CommonTestUtils.createClassNotInClassPath() to not use Unsafe.defineClass()
                 Key: FLINK-13451
                 URL: https://issues.apache.org/jira/browse/FLINK-13451
             Project: Flink
          Issue Type: Improvement
          Components: core
    Affects Versions: 1.9.0
            Reporter: Stephan Ewen
             Fix For: 1.10.0


The method {{Unsafe.defineClass()}} is removed in Java 11.
To support Java 11, we need to rework the method {{ CommonTestUtils.createClassNotInClassPath()}} to use a different mechanism.

Java 11 introduces a new way to define a class from byte code via {{MethodHandles}}. However, because these do not exist in Java 8, we cannot use them if we want to keep supporting Java 8, which we most likely want to do for quite a while.

A method that works across both versions is to write the class byte code out to a temporary file and create a new URLClassLoader that loads the class from that file.

That solution is not a complete drop-in replacement, because it cannot add the class to an existing class loader, but can only create a new pair of (classloader & new-class-in-that-classloader). But it is seems straightforward to adjust the existing tests to work with that.



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