Sophie Blee-Goldman created KAFKA-9134:
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Summary: Refactor the StreamsPartitionAssignor for more code
sharing with the FutureStreamsPartitionAssignor
Key: KAFKA-9134
URL: https://issues.apache.org/jira/browse/KAFKA-9134
Project: Kafka
Issue Type: Improvement
Components: streams
Reporter: Sophie Blee-Goldman
Frequently when fixing bugs in the StreamsPartitionAssignor, version probing,
or other assignor-related matters, we make a change in the
StreamsPartitionAssignor and re-run the version_probing_upgrade system test
only to see that the issue is not fixed because we forgot to mirror that change
in the FutureStreamsPartitionAssignor. Worse yet, we are making a new change or
fixing something that doesn't directly affect version probing, so we update
only the StreamsPartitionAssignor and don't even run the version probing test,
and discover later the version probing system test has started failing. Then we
often waste time digging through old changes just to discover it was just
because we forgot to copy any changes to the StreamsUpgradeTest classes
(includes also it's future version of the SubscriptionInfo and AssignmentInfo
classes)
We should refactor the StreamsPartitionAssignor so that the future version can
rely more heavily on the original class. This will probably involve either or
all of:
* making the class's latestSupportedVersion configurable in the constructor,
to be used only by the system test. this will probably also require making it
configurable in some other classes such as SubscriptionInfo and AssignmentInfo
* breaking up the methods such as onAssignment and assign so that the future
assignor can call smaller pieces at a time – part of the original problem is
that the normal assignor will throw an exception partway through these methods
if the latest version is a "future" one, so we end up having to call the
method, catch the exception, and recode the remainder of the work in that method
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