On Tue, 11 Oct 2022 01:56:38 GMT, Stuart Marks <sma...@openjdk.org> wrote:
>> Tagir F. Valeev has updated the pull request incrementally with one >> additional commit since the last revision: >> >> Remove Random -> ThreadLocalRandom change > > test/jdk/java/util/Collections/Shuffle.java line 66: > >> 64: RandomGeneratorFactory<RandomGenerator> factory = >> RandomGeneratorFactory.getDefault(); >> 65: list.sort(null); >> 66: Collections.shuffle(list, factory.create(1)); > > This assumes that the default factory will accept a seed value that > initializes its state so that the pseudorandom sequence is repeatable. Not an > unreasonable assumption, but `create(long)` essentially says that it can > ignore the seed, and `getDefault` says the algorithm may change over time. On > the other hand if something does change such that the pseudorandom sequence > isn't repeatable, this test will most likely fail immediately. I was poking > around for an explicit way to request some kind of PRNG that's guaranteed to > be started in repeatable state, but I couldn't find one. Hmmm. Oh, that's an unfortunate detail, I didn't know about this. We can explicitly request a JumpableGenerator, like "Xoshiro256PlusPlus" and then copy it via `copy()` method. What do you think? ------------- PR: https://git.openjdk.org/jdk/pull/10520
