Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/2300
Looks mostly good. I noticed a few things:
I am not quite sure about the lazy initialization. The idea is good, but
the current double-check-locking pattern is not multi-thread safe
(http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html).
Either we make each access a little more expensive (declare the field
`volatile`), or we eagerly initialize the maps.
As a followup, we should probably look into adjusting the JMX reporter. Is
there a way we can expose all tags?
Can you also rebase this to the latest master? It has a bunch of merge
conflicts right now, when trying to test it.
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