Github user zentol commented on a diff in the pull request: https://github.com/apache/flink/pull/2300#discussion_r75190837 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/metrics/groups/AbstractMetricGroup.java --- @@ -83,9 +88,25 @@ // ------------------------------------------------------------------------ - public AbstractMetricGroup(MetricRegistry registry, String[] scope) { + public AbstractMetricGroup(MetricRegistry registry, String[] scope, A parent) { this.registry = checkNotNull(registry); this.scopeComponents = checkNotNull(scope); + this.parent = parent; + } + + public Map<String, String> getAllVariables() { + if (variables == null) { // avoid synchronization for common case --- End diff -- Yeah, `isEmpty()` wouldn't work. I checked my implementation and for JMX it would not be the data-processing thread that calls ´getAllVariables()`, so this would in fact be alright. For our current non-JMX reporters this would be done in the respective reporter thread.
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