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

[Martin Buchholz]

[+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.