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![]() However, exploiting this fact is far from trivial: The best you can do is create a Thread that loops continuously on Thread.sleep(1) and increment a counter on each loop iteration, thus hopefully providing you with a better "clock" than System.currenTimeMillis(). Repeating the same experiment with Thread.sleep(long) will show an improvement because Sun Microsystems' JVM implementation makes special provisions for this method so it can deliver 1-ms resolution. For now, realize that I, of course, could not use System.currenTimeMillis() to measure resolution of anything that might be better than that method.)Ĭlearly, using Object.wait(long) with inputs smaller than 10 ms does not work as expected. (You might be wondering about the mysterious ITimer timer object above. On the same system used for the first experiment, this results in: duration = 5.678 ms + format.format (timer.getDuration ()) + " ms") Thread.currentThread ().sleep (0, 500) offered by other Java time-related methods: Uncomment various lines below to see the resolution Create an ITimer using the Factory class:įinal ITimer timer = TimerFactory.newTimer () įinal Object lock = new Object () // used by monitor.wait() below Public static void main (String args) throws Exceptionįinal DecimalFormat format = new DecimalFormat () #ITIMER INTERNET CAFE SOFTWARE DOWNLOAD CODE#Unfortunately, these are not good alternatives either, as the following code demonstrates: Occasionally, you can find alternative suggestions based on Object.wait(long) or Thread.sleep(long) methods. If you cannot loop over code being profiled a sufficient number of times to get the cumulative execution time in this range, you need another approach. On the system used above, System.currentTimeMilllis() is suitable only for profiling relatively long-lasting (100 ms and longer) operations. You should see now that this is naive at best. #ITIMER INTERNET CAFE SOFTWARE DOWNLOAD FULL#Java developer forums are full of arguments about whether a particular language trick offers performance advantages, with developers presenting "proofs" based on System.currentTimeMilllis() returning "0 ms versus 10 ms" for some new way of implementing a particular code paradigm. In most cases, the actual resolution has nothing to do with the fact that System.currenTimeMillis()'s return value is current time in milliseconds. #ITIMER INTERNET CAFE SOFTWARE DOWNLOAD WINDOWS#Java developers on Linux enjoy 1-millisecond (ms) resolution, while Windows 98 users suffer with 50-ms resolution. ![]() You will discover that results vary based on your platform. When run in JDK 1.4.1 on a Windows 2000 system, produces the following: delta = 10 ms ("delta = " + (time - time_prev) + " ms") Long time = System.currentTimeMillis (), time_prev = time For (int r = 0 r < 3000 ++ r) System.currentTimeMillis () ![]()
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