[concurrency-interest] @Contended (JEP-142)

Stanimir Simeonoff stanimir at riflexo.com
Thu Nov 29 09:06:02 EST 2012


On Thu, Nov 29, 2012 at 12:40 PM, Stanimir Simeonoff
<stanimir at riflexo.com>wrote:
>
>> Problem w/ sun.misc is that it requires security permissions on runtime
>> whilst it's an absolutely harmless operation. To avoid that people will
>> just keep padding like it's done now - i.e. nothing achieved.
>>
>
>
>
>> For instance, I can live by extending j.u.c.atomics even it's ugly just
>> to avoid touching Unsafe itself (or the AtomicUpdaters)
>
>
> That doesn't address the need for padding.
>

It's a similar example when you can skip resorting to the Unsafe (and keep
performance) - there is a way to do it even if it's ugly. Similar fate may
follow sun.misc.Contended - even now it's possible to emulate padding but
an attempt to improve the case by having it in sun.misc is neither portable
nor a security friendly approach.

Stanimir


>
>>
>> Stanimir
>>
>>
>> On Thu, Nov 29, 2012 at 1:00 PM, Dr Heinz M. Kabutz <
>> heinz at javaspecialists.eu> wrote:
>>
>>> **
>>> IMHO, sun.misc.Contended is the right place for this one, as it will
>>> hopefully discourage people from using it, unless they really know what
>>> they are doing.  Next you find programmers making all their fields
>>> "Contended", because they read on some blog that it makes things faster.
>>> Then instead of your object using only 32 bytes, it gets bloated to 512
>>> bytes.
>>>
>>> Regards
>>>
>>> Heinz
>>> --
>>> Dr Heinz M. Kabutz (PhD CompSci)
>>> Author of "The Java(tm) Specialists' Newsletter"
>>> Sun Java Champion
>>> IEEE Certified Software Development Professionalhttp://www.javaspecialists.eu
>>> Tel: +30 69 75 595 262
>>> Skype: kabutz
>>>
>>>
>>>
>>> On 11/29/12 11:11 AM, Stanimir Simeonoff wrote:
>>>
>>> >>Any concrete suggestion? j.u.c.Contended? j.u.c.hints.Contended?
>>> j.u.c.expert.Contended?
>>> I'd go with "hints".
>>>
>>> Stanimir
>>>
>>>
>>> On Thu, Nov 29, 2012 at 11:43 AM, Aleksey Shipilev <
>>> aleksey.shipilev at oracle.com> wrote:
>>>
>>>> On 11/28/2012 08:42 PM, Gregg Wonderly wrote:
>>>> > Going down that path, makes me feel like having it in a more "public"
>>>> > package would be a better choice.  The name "Contended" is now going
>>>> to
>>>> > be a "reserved" name for many people, when used in annotation form.
>>>>  So,
>>>> > why not just make it a publicly defined "annotation" which has
>>>> > appropriate implementation in appropriate environments?
>>>>
>>>>  Any concrete suggestion? j.u.c.Contended? j.u.c.hints.Contended?
>>>> j.u.c.expert.Contended?
>>>>
>>>> -Aleksey.
>>>>
>>>>
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>>>
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>>
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>>
>
>
> --
> Viktor Klang
>
> Akka Tech Lead
> Typesafe <http://www.typesafe.com/> - The software stack for applications
> that scale
>
> Twitter: @viktorklang
>
>
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