On Wed, 14 Feb 2024 23:37:03 GMT, Stuart Marks <sma...@openjdk.org> wrote:
>> Somewhat surprisingly, `ArrayList$Sublist.sort()` is not specialized and >> will thus fall back to slower default method of `List.sort()` instead of >> sorting a range of the array in-place in its backing root `ArrayList`. >> >> This doesn't change observable behavior, so haven't added tests, and `tier1` >> tests still all pass except for >> `test/jdk/java/util/Locale/LocaleProvidersFormat.java` which also currently >> fails on master too on the machine I tested on. > > (Discussion mainly of historical interest.) > > @pavelrappo Correct, historically, `Collections.sort` would fail to sort > `CopyOnWriteArrayList`. You have to go back to JDK 7 to see this. The sorting > approach used by `Collections.sort` (still present in the default > implementation of `List.sort`) gets an array using `toArray()`, sorts it, and > then copies the sorted elements back using `ListIterator.set`. Since > `CopyOnWriteArrayList` doesn't support modifications using `ListIterator`, it > fails with `UnsupportedOperationException`. The overrides of `List.sort` have > fixed this problem. > > COWAL still has some problems with other things that use similar techniques, > such as `Collections.shuffle`. That uses get/set to swap elements, which > COWAL does support, but it copies the array on each set() operation. This > results in N copies of the array being made for an N-element list. Hey folks (@stuart-marks or @JimLaskey) it's been a while – can I get a review? ------------- PR Comment: https://git.openjdk.org/jdk/pull/17818#issuecomment-2049131137
