Github user tison1 commented on the pull request: https://github.com/apache/flink/commit/8231b62ff42aae53ca3a7b552980838ccab824ab#commitcomment-29765803 In flink-runtime/src/main/java/org/apache/flink/runtime/jobmanager/scheduler/CoLocationGroup.java: In flink-runtime/src/main/java/org/apache/flink/runtime/jobmanager/scheduler/CoLocationGroup.java on line 81: here is a question from 4 years later. why this method call `ensureCapacity` twice. it seems to solve some issue about concurrency but as the change made in #6353 , this method throws a out of index exception. so i try to add a synchronized block to make sure it is thread-safe #6370 . definitely i think my code is not that perfect. so i come to here, wonder the original purpose of this code and ask advice about the two PRs mentioned above @StephanEwen looking forward to your advice. thanks in advance!
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