GitHub user guozhangwang opened a pull request:
https://github.com/apache/kafka/pull/2485
KAFKA-3896: Fix KStream-KStream leftJoin
The issue of transiently having duplicates is due to the bad design of the
left join itself: in order to ignore the partial joined results such as
`A:null`, it lets the producer to potentially send twice to source stream one
and rely on all the following conditions to be true in order to pass the test:
1. `receiveMessages` happen to have fetched all the produced results and
have committed offsets.
2. streams app happen to have completed sending all result data.
3. consumer used in `receiveMessages` will complete getting all messages in
a single poll().
If any of the above is not true, the test fails.
Fixed this test to add a filter right after left join to filter out partial
joined results. Minor cleanup on integration test utils.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/guozhangwang/kafka
K3896-duplicate-join-results
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/kafka/pull/2485.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #2485
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commit 186c32075bb8cab217dddeb23aa341fb3ac5e5d0
Author: Guozhang Wang <wangg...@gmail.com>
Date: 2017-02-02T06:51:57Z
fix left join
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