Slow SecureRandom initialization

Suppose you do simple thing:

public class Main {
    public static void main(String[] args) {
        long started = System.currentTimeMillis();
        try {
            new URL(args[0]).openConnection();
        } catch (Exception ignore) {
        }
        System.out.println(System.currentTimeMillis() - started);
    }
}

Now run it with http://localhost as args[0]

It takes ~100 msec to complete.

Now try https://localhost

It takes 5000+ msec.

Now run the same thing on linux or in docker:

• http: ~100 msec
• https: ~350 msec

Why is this? Why such a huge difference between platforms? What can you do about it?

For long-running application servers and applications with their own long and heavy initialization sequence, these 5 seconds may not matter.

However, there are plenty of applications where this initial 5sec "hang" matters and may become frustrating...