nextDouble calls next, which according to Java 5 docs is:
synchronized protected int next(int bits) {
seed = (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1);
return (int)(seed >>> (48 - bits));
}
This is exactly the kind of thing I think we shouldn't have to worry
about in Clojure.
Stuart
> Looks like the only synchronization is for lazy initialization of the
> instance of Random used by the static method:
>
> public final class Math {
>
> private static Random randomNumberGenerator;
>
> private static synchronized void initRNG() {
> if (randomNumberGenerator == null)
> randomNumberGenerator = new Random();
> }
>
> public static double random() {
> if (randomNumberGenerator == null) initRNG();
> return randomNumberGenerator.nextDouble();
> }
>
> }
>
> public class Random implements java.io.Serializable {
> public Random() { this(++seedUniquifier + System.nanoTime()); }
> private static volatile long seedUniquifier = 8682522807148012L;
>
> public double nextDouble() {
> long l = ((long)(next(26)) << 27) + next(27);
> return l / (double)(1L << 53);
> }
> }
>
> On Dec 2, 12:04 am, Stuart Halloway <[EMAIL PROTECTED]> wrote:
>> Clojure's rand delegates to Java's Math.random(), which I am pretty
>> sure has a synchronized block in it.
>>
>> One problem with living on top of Java is calling into methods that
>> have no (conceptual) need to be synchronized. This could hurt
>> performance in an app carefully written in Clojure to avoid mutable
>> state and locking. Since unsynchronized PRNGs exist, I would suggest
>> we modify rand to use one. (I am willing to take the lead on writing
>> one in Clojure if needed.)
>>
>> Thoughts?
>>
>> Stuart
> >
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