Github user StefanRRichter commented on a diff in the pull request:
https://github.com/apache/flink/pull/5908#discussion_r185729269
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/HeapInternalTimerService.java
---
@@ -49,13 +50,13 @@
/**
* Processing time timers that are currently in-flight.
*/
- private final Set<InternalTimer<K, N>>[] processingTimeTimersByKeyGroup;
+ private final Map<String, InternalTimer<K, N>>[]
processingTimeTimersByKeyGroup;
--- End diff --
It seems that you switch from set to map because you want to use
`ConcurrentHashMap`, but you can simply have a set that is backed by
`ConcurrentHashMap` either from `Collections.newSetFromMap(...)` or
`ConcurrentHashMap.newKeySet()`
---
