Oleg Kalnichevski wrote:
On Thu, Aug 18, 2005 at 10:39:02AM +0200, Ortwin Gl?ck wrote:
Oleg Kalnichevski wrote:
Odi,
(1) Please take a closer look at the exception stack trace. The exception
is thrown when the server socket gets interrupted while blocked in the
listen method. This exception is perfectly legitimate in this context
Okay.
(2) This should not really require a PhD Stanford to figure out that if
you hardware is faster that the one I used to run the test you might
want to tweak the parameters a little in order to make the numbers a
little more representative. Please increase the buffer size and retest
Ok, with 10 times as much data (10 MB), I get:
Old IO average time (ms): 121
Blocking NIO average time (ms): 119
NIO with Select average time (ms): 133
The jitter is now around 10-15%. So the three values still are all in
the same statistical bucket. That means there is no notable performance
difference below 10 MB of data.
Odi,
I think 10-15% performance penalty is considerable.
10-15% is the *jitter*, not the performance penalty. If I measure 133 ms
for NIO then these 133 ms are an avarage of 20 individual values with 15
ms of uncertainity each. That means the value 133 ms has an uncertainity
of 15 ms as well (which is 11%) : The "real" value is between 118 and
148 ms. So the above numbers have the following meaning:
Old IO average time (ms): 106 - 136
Blocking NIO average time (ms): 104 - 134
NIO with Select average time (ms): 118 - 148
or graphically:
******************************* [IO]
******************************* [bIO]
[nbIO] *******************************
|---------|---------|---------|---------|---------|
100 110 120 130 140 150
Thus it may be possible that, despite the actual figures, nbIO is
actually faster than IO.
Sorry for being pedantic. It's just that I am a physicist and I was
taught how to properly perform a measurement.
> Besides, on some
platforms, admittedly misconfigured or having poor JRE implementation,
the cost of having a channel selector per channel is simply prohibitive.
I am still of an opinion we gain absolutely nothing by using NIO for
API that is not specifically designed to make heavy use of non-blocking
IO with hundreds of channels managed by one channel selector.
Oleg
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