Time on multi-core, multi-socket servers
In Distributed Computing the notion of "when-ness" is fundamental; Lamport's "Time, Clocks, and the. Ordering of Events in a Distributed System" paper is considered one of the foundational pieces of work.
But what about locally?
The conclusion is that except for the special case of using nanoTime() in micro benchmarks, you may as well stick to currentTimeMillis() —knowing that it may sporadically jump forwards or backwards. Because if you switched to nanoTime(), you don't get any monotonicity guarantees, it doesn't relate to human time any more —and may be more likely to lead you into writing code which assumes a fast call with consistent, monotonic results.
Details: http://steveloughran.blogspot.ca/2015/09/time-on-multi-core-multi-socket-servers.html
But what about locally?
The conclusion is that except for the special case of using nanoTime() in micro benchmarks, you may as well stick to currentTimeMillis() —knowing that it may sporadically jump forwards or backwards. Because if you switched to nanoTime(), you don't get any monotonicity guarantees, it doesn't relate to human time any more —and may be more likely to lead you into writing code which assumes a fast call with consistent, monotonic results.
Details: http://steveloughran.blogspot.ca/2015/09/time-on-multi-core-multi-socket-servers.html
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