RFR: 8062194: java.util.jar.Attributes should use insertion-ordered iteration

Xueming Shen xueming.shen at oracle.com
Tue Oct 28 18:24:21 UTC 2014

Martin, I can help the CCC, it is fair quick these days given this is a really simple update,
just couple days.


On 10/28/2014 11:09 AM, Martin Buchholz wrote:
> Xueming, I understand that getting CCC approval is a fair amount of
> work.  At your option, we could leave the spec unchanged and do
> without CCC, given that Attributes' iteration order has changed in
> every past release.  Or we could split the spec change off as a
> separate improvement.
> On Mon, Oct 27, 2014 at 12:15 PM, Martin Buchholz<martinrb at google.com>  wrote:
>> [+core-libs-dev oops I forgot to cc: the first time...]
>> On Mon, Oct 27, 2014 at 12:02 PM, Xueming Shen<xueming.shen at oracle.com>
>> wrote:
>>> On 10/27/2014 11:33 AM, Martin Buchholz wrote:
>>>> Hello Xueming, Alan,
>>>> I'd like you to do a code review.
>>>> http://cr.openjdk.java.net/~martin/webrevs/openjdk9/Attributes-iteration-order/
>>>> <http://cr.openjdk.java.net/%7Emartin/webrevs/openjdk9/Attributes-iteration-order/>
>>>> https://bugs.openjdk.java.net/browse/JDK-8062194
>>> The change looks fine. But guess we might have to go through the CCC for
>>> this one,
>>> given the nature of its "incompatibility"?
>> Yes - technically, this is a small incompatibility.  (But Attribute
>> iteration order has changed many times)
>>> Btw, is there any "noticeable" performance concern of switching from
>>> hashmap to linkedhashmap?
>>> Guess, we might have use scenario that lots of attributes is being access
>>> when lots of jar get
>>> opened the same time...
>> LinkedHashMap uses a "little more" cpu and memory.  The cost is small enough
>> that some people have suggested simply replacing HashMap's implementation
>> with that of LinkedHashMap, and that is not totally crazy, but we're not
>> going that far.  Attributes are unlikely to contain many elements or to be
>> long-lived.

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