Integrated: 8343426: ConcurrentSkipListMap.spliterator() can no longer split the stream

[kabutz]

On Fri, 1 Nov 2024 10:13:15 GMT, kabutz <duke at openjdk.org> wrote:

> Since Java 10, spliterators for the ConcurrentSkipListMap were pointing to the head, which has item == null, rather than to the first element. The trySplit() method no longer worked, and always returned null. Therefore, parallel streams have not worked for ConcurrentSkipListMap and ConcurrentSkipListSet since Java 10. It worked correctly in Java 8 and 9.
> 
> The problem lies in the constructor calls for the various spliterators. In Java 9, we pass in head.node.next as "origin" into the  constructor. In Java 10, this was changed to just head.node as "origin". Since the "item" field is always null on head.node, we never enter the first if() statement in the trySplit() method and thus it always returns null.

This pull request has now been integrated.

Changeset: 2b57f402
Author:    Dr Heinz M. Kabutz <heinz at javaspecialists.eu>
Committer: Viktor Klang <vklang at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/2b57f402c46104d4aba784a891ba90604f5e9e4c
Stats:     40 lines in 2 files changed: 31 ins; 0 del; 9 mod

8343426: ConcurrentSkipListMap.spliterator() can no longer split the stream

Co-authored-by: Doug Lea <dl at openjdk.org>
Reviewed-by: vklang

-------------

PR: https://git.openjdk.org/jdk/pull/21820