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Hudson commented on COLLECTIONS-409: ------------------------------------ Integrated in commons-collections #23 (See [https://builds.apache.org/job/commons-collections/23/]) [COLLECTIONS-409] Improve performance of ListOrderedSet#addAll, add missing javadoc. Thanks to Adrian Nistor for reporting and providing a patch. (Revision 1351821) Result = SUCCESS tn : http://svn.apache.org/viewvc/?view=rev&rev=1351821 Files : * /commons/proper/collections/trunk/src/main/java/org/apache/commons/collections/set/ListOrderedSet.java > ListOrderedSet.addAll() is very slow > ------------------------------------ > > Key: COLLECTIONS-409 > URL: https://issues.apache.org/jira/browse/COLLECTIONS-409 > Project: Commons Collections > Issue Type: Bug > Affects Versions: 3.2.1 > Environment: java 1.6.0_24 > Ubuntu 11.10 > Reporter: Adrian Nistor > Fix For: 4.0 > > Attachments: Test.java, patch.diff > > > Hi, > I am encountering a performance problem in ListOrderedSet.addAll(). > It appears in version 3.2.1 and also in revision 1351465 (18 Jun > 2012). I have attached a test that exposes this problem and a > three-line patch that fixes it. On my machine, for this test, the > patch provides a 79X speedup. > To run the test, just do: > $ java Test > The output for the un-patched version is: > Time is 1837 > The output for the patched version is: > Time is 23 > As the patch shows, the problem is that > ListOrderedSet.addAll(int index, Collection<? extends E> coll) > performs: > "setOrder.add(index++, e)" for each element in "coll". This is very > expensive, because "setOrder" is an ArrayList, and inserting an > element in the middle of an ArrayList shifts all the elements to the > right. > The patched version avoids this cost by inserting all the elements at > once, thus performing only one insert. > Is this a bug? If so, can you please confirm that the patch is > correct? > Thanks, > Adrian -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira