RFR: 8372946 - TreeMap sub-map entry spliterator is expensive [v4]

[Oli Gillespie]

On Mon, 23 Feb 2026 13:48:14 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Oli Gillespie has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Use Spliterators.spliteratorUnknownSize
>
> test/jdk/java/util/stream/test/org/openjdk/tests/java/util/stream/CollectionAndMapModifyStreamTest.java line 123:
> 
>> 121: 
>> 122:         // The following are not lazy
>> 123: //        maps.put(TreeMap.class.getName() + ".descendingMap()", () -> new TreeMap<>(content).descendingMap());
> 
> Is this test modification still necessary?

That case still fails, yes, but I'm not totally sure why. I'm looking into it.


java.util.ConcurrentModificationException
	at java.base/java.util.TreeMap$NavigableSubMap$SubMapIterator.prevEntry(TreeMap.java:2070)
	at java.base/java.util.TreeMap$NavigableSubMap$DescendingSubMapEntryIterator.next(TreeMap.java:2121)
	at java.base/java.util.TreeMap$NavigableSubMap$DescendingSubMapEntryIterator.next(TreeMap.java:2114)
	at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
	at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1939)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:570)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:560)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:635)
	at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:291)
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:652)
	at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:658)
	at org.openjdk.tests.java.util.stream.CollectionAndMapModifyStreamTest.testEntrySetSizeRemove(CollectionAndMapModifyStreamTest.java:164)
	at org.openjdk.tests.java.util.stream.CollectionAndMapModifyStreamTest.testMapEntriesSizeRemove(CollectionAndMapModifyStreamTest.java:155)

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PR Review Comment: https://git.openjdk.org/jdk/pull/28608#discussion_r2841102126