Jason & Stuart, Yes, the intent was to leave the backing array the same size in order to avoid to have the resize of it when a new element is added. So, if someone wanted to reduce the size of the backing array then they could use the ArrayList.trimToSize() method.
However, if you are saying (in another post - http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-December/057560.html ) that the 'trimming' of the backing array on a copy is intentional and that you are OK with a subsequent addition then resizing the backing array again - causing 2 resize operations, then this makes this performance change a moot issue. I can also see that not trimming on a copy is a change in the behavior and could cause problems with existing usages of this behavior. I thank you for all your comments and suggestions but it seems this change will not be suitable. Thanks Steve Groeger IBM Runtime Technologies Hursley, Winchester Tel: (44) 1962 816911 Mobex: 279990 Mobile: 07718 517 129 Fax (44) 1962 816800 Lotus Notes: Steve Groeger/UK/IBM Internet: groe...@uk.ibm.com Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU From: Jason Mehrens <jason_mehr...@hotmail.com> To: Martin Buchholz <marti...@google.com>, Stuart Marks <stuart.ma...@oracle.com> Cc: core-libs <core-libs-dev@openjdk.java.net> Date: 19/12/2018 04:54 Subject: Re: Proposal: ArrayList constructor perforrmance improvement Sent by: "core-libs-dev" <core-libs-dev-boun...@openjdk.java.net> >Sorry for not having remembered the history. **Start the wavy motion effect because we are going back in time! ====== Date: Wed, 27 Sep 2006 16:49:47 -0700 From: Martin Buchholz <martin.buchh...@sun.com> Subject: 6347106 (coll) Make ArrayList(Collection) more threadsafe Sender: <martin.buchh...@sun.com> To: Jason Mehrens <jason_mehr...@hotmail.com> Hi Jason, Thanks for the SDN comment. I updated 4759223 and 4918916. I closed 4759223 as a dup of 6347106, but 4918916 is still an issue (although I should probably close as Not a Defect, following Josh). ====== So most of the history is in the following: https://bugs.openjdk.java.net/browse/JDK-4918916 https://bugs.openjdk.java.net/browse/JDK-4759223 https://bugs.openjdk.java.net/browse/JDK-6347106 Yes I still have this email and that Sun Ultra 20 from the Mustang Regressions challenge :) Jason Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
