Ok, now I see how #4049 is relevant. Two things need to be done: 1) Highlight, by adding comments, that `StringDimensionIndexer`s are updated before `indexIncrement` (which is better renamed to something like `lastRowIndex`) is incremented. (To ensure this is not violated during some refactoring.) 2) Simple `ArrayList` is still not enough. This line in the `ArrayList`'s `grow()` method: ```java elementData = Arrays.copyOf(elementData, newCapacity); ``` Lacks a write barrier between `Arrays.copyOf()` and the assignment. It means that a parallel thread may read the new array from the `elementData` field before seeing effects of `Arrays.copyOf()`. This could be fixed by creating a minimal implementation of `ArrayList` with `volatile` `elementData` (without any CAS or CoW logic that I mentioned earlier).
[ Full content available at: https://github.com/apache/incubator-druid/issues/6322 ] This message was relayed via gitbox.apache.org for devnull@infra.apache.org
