bbeaudreault opened a new pull request, #5149: URL: https://github.com/apache/hbase/pull/5149
Spotbugs complains because, for example, the assignment of `appendHisto` is synchronized but the actual usage in `updateAppend` is not. The first thought might be to synchronize all of the methods, but that would be detrimental to performance and unnecessary since these metrics are already thread safe. The synchronization of register/deregister was added as part of the LossyCounting stuff for user metrics. So its possible under extreme conditions for the LossyCounting thread to deregister a user source which is currently being registered. So it's important to synchronize the actual metric creation/removal, more than anything else. There is only one caller of `register/deregister`, here in [MetricsUserAggregateSourceImpl](https://github.com/apache/hbase/blob/master/hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsUserAggregateSourceImpl.java#L50-L87). Note that it's already synchronized. So I think the synchronization here is redundant. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
