Performance of Random UUID generation with Java 7 or Java 6

Question

I have a web based Java application that generates random UUIDs for session information. One of our testers is claiming up to 350ms to generate UUIDs based upon his own profiling, but I have not yet been able to replicate his results. He points to this article http://www.cowtowncoder.com/blog/archives/2010/10/entry_429.html to help back up his results. I wanted to see if anyone else has ran into this limitation with Java's built-in UUID generation capability in either Java 6 or Java 7 applications.

Answer 1

I tested it

    for (;;) {
        long t0 = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            UUID.randomUUID();
        }
        System.out.println(System.currentTimeMillis() - t0);
    }

on my PC it is ~1100 ms, which is pretty slow. UUID.randomUUID() uses SecureRandom internally, to make it faster we can use regular java.util.Random

    Random r = new Random();
    for (;;) {
            ..
            new UUID(r.nextLong(), r.nextLong());

it's ~80 ms