[12]RFR 8205399 : Set node color on pinned HashMap.TreeNode deletion (original) (raw)

Martin Buchholz martinrb at google.com
Wed Aug 8 20:23:29 UTC 2018


Brent, thanks for writing a test. I would probably not have bothered. Or if I was ambitious, I might have written a whitebox test against all the red-black tree implementations in the core libs, verifying node color.

final?

implements Comparable ?

Buggy - use Integer.compare instead. https://download.java.net/java/early_access/jdk12/docs/api/java.base/java/lang/Integer.html#compare(int,int)

Approved.

On Wed, Aug 8, 2018 at 11:57 AM, Brent Christian <brent.christian at oracle.com

wrote:

Hi,

Please review the following fix. Bug: https://bugs.openjdk.java.net/browse/JDK-8205399 Webrev: http://cr.openjdk.java.net/~bchristi/8205399/webrev01/ The vmTestbase/vm/gc/containers/Combination05/TestDescription.java test, which does random adds and removes (via Iterator), has been failing intermittently with an AssertionError. I tracked down a couple sequences of operations that trigger the assertion. Sufficient HashMap collisions convert a bin to a tree, and then values are deleted using Iterator.remove() (pinned node deletion). The condition that fails in HashMap.TreeNode.checkInvariants() is: if (t.red && tl != null && tl.red && tr != null && tr.red) A red TreeNode should not have two red children. Many thanks to Doug Lea for providing the fix for the HashMap red/black tree code. The root node color needs to be set in this case. Thanks, -Brent



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