[GitHub] storm issue #2800: STORM-3162: Fix concurrent modification bug

[srdo]

Github user srdo commented on the issue:

    https://github.com/apache/storm/pull/2800
  
    Regarding performance, consider that Nimbus is already copying 
`heartbeatCache` on writes everywhere else 
https://github.com/apache/storm/blob/master/storm-server/src/main/java/org/apache/storm/daemon/nimbus/Nimbus.java#L4636-L4639.
    
    Changing `StatsUtil.updateHeartbeatCache` to return a new Map and using 
`Assoc` to update `heartbeatCache` would be my preferred solution.


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