Re: The first 10 files

Robert Klemme <>
Fri, 15 Mar 2013 11:38:02 +0100
On 14.03.2013 11:07, Wojtek wrote:

So NIO is about 4-5 times faster than IO. The first NIO run looks like
an anomoly, might be some JRE loading happening.

All the runs produce different timings, might be a Windows caching
effect. However the NIO is consistently much faster overall.

I am not convinced that this conclusion is warranted. There are a few
factors which I believe make your conclusion questionable:

- You included class loading time in your measurement. For example,
assuming that all io functionality is implemented on top of nio it would
be logical to expect more classes to be loaded. There are a number of
use cases where it matters - but there are also use cases where it
doesn't matter (long running servers).

- Generally we are dealing with quite low timings (around 100ms) and
relatively high variations. Also the test was made on Windows and the
System.currentTimeMillis() is known to be imprecise on that platform (in
the order of tens of milliseconds).

- Your io approach does not use FileFilter which some have suggested to
be a way to avoid constructing a large result array.

- The test is an artificial situation. With all factors like JVM
involved it may be that in a realistic application things look different
to an extent that the differences you measured here do not matter any more.

Kind regards


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