Valentino Proietti created KAFKA-6486:
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Summary: TimeWindows causes unordered calls to windowed
aggregation functions
Key: KAFKA-6486
URL: https://issues.apache.org/jira/browse/KAFKA-6486
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 1.0.0
Reporter: Valentino Proietti
This is not a real bug but it causes some weird behaviour, at least in my
opinion.
The TimeWindows has a method called windowsFor() that uses and returns an
HashMap:
@Override
*public* Map<Long, TimeWindow> windowsFor(*final* *long* timestamp) {
*long* windowStart = (Math._max_(0, timestamp - sizeMs + advanceMs) /
advanceMs) * advanceMs;
*final* Map<Long, TimeWindow> windows = *new* HashMap<>();
....
the HashMap does not preserve the order of insertion and this ends up later in
calls to any streams windowed aggregation functions that are not ordered by
window time as I would expect.
A simple solution is to replace the HashMap with a LinkedHashMap and that's
what I did.
Anyway replacing it directly in your code can save hours of debugging to
understand what's happening.
Thank you
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