NonBlockingStatsDClient is not thread-safe

The class NonBlockingStatsDClient is not thread-safe (and presumably it should be). The reason for this is that a static NumberFormat instance is shared among all threads, but this class itself is not thread-safe. See the "synchronization" section of the NumberFormat docs:

http://docs.oracle.com/javase/6/docs/api/java/text/NumberFormat.html

To fix this problem, either create a new NumberFormat for each call, or create one per thread, using a ThreadLocal<NumberFormat>

http://stackoverflow.com/questions/1285279/java-synchronization-issue-with-numberformat

I guess this could be closed now unless there are some other reasons to suspect this class is not thread-safe

[krishna81m]

Just to confirm, do you expect us to write threadlocal implementations to return the same StatsDClient per thread and cleanup/remove() after request is processed or it is already done internally?

@krishna81m AFAIK this class is thread-safe, so you can share instances of it among threads

[krishna81m]

Thanks, then, should we use thread local to get any performance benefits just in case there is any synchronization?

I don't know if using a thread local would give you a performance benefit. I think only you can determine this by measuring the performance of your system with and without a thread local.