Re: Tuning suggestions, please?

Patricia Shanahan <>
Wed, 04 Jul 2007 08:32:03 -0700
Bret Schuhmacher wrote:

Thanks for the code, Nigel. Here's the output:
15 193573
16 186582
16 190201
15 183223
16 116424
16 123012
15 100954
16 183436
15 170407
16 180246
16 195359
15 186473
16 190119
16 148391

Looks like the timer resolution on my laptop running Windows XP is 15-16ms -
consistent with the 15-16 ms I was trying to track down.

I originally saw the issue at a customer's site on an AIX v5.2 box and
replicated it on my Windows laptop. Is it possible an AIX box has the same
timer resolution a Windows box does? I see the same issues inside and
outside of Eclipse, as well as under different JVM versions (for those of
you who were asking).

Is there *anything* I can do about this? Sounds like it's hardwired into
the CPU. I tried adding this:
        Thread thisThread = Thread.currentThread();
But it didn't help.

Are there other ways of dedicating a CPU or increasing the timeslice or
priority to a thread in Java? Would it help?

You still seem to be looking for something like context switches that
would cause intermittent delays. However, the message from the timer
resolution measurement is that all you know is the average time for a
series of calls. Maybe there are intermittent delays. Maybe every single
call takes between 8.5 and 8.7 milliseconds. Both are consistent with
the data.

The next step should be to redo the measurement, using
System.nanoTime(). That will tell you what type of problem you are
looking for.


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