New

[Howard Lovatt]

This is a two way argument, you could equally say can you demonstrate that
the *compiler* can optimize my point 4 correctly. I am not suggesting that
the JVM must optimize the creation away, just that it optionally can. If you
are clear were the object is potentially created then the programmer can
always do the optimization (just like the programmer already does for normal
objects and is reminded to do so by the new keyword).

On 29 March 2010 22:46, Osvaldo Doederlein <opinali at gmail.com> wrote:

> I have an idea to settle this debate and avoid further fight: a design that
> depends on advanced optimization (either EA or some new one) should only be
> considered as soon as we have, at least in alpha stage, said optimization in
> the JDK7 project. And by "we have it" I imply that we also have specific
> benchmarks that shows that the optimization does indeed eliminate the cost
> it should. So, I'm not content with a microbenchmarks of non-lambda code
> (e.g. en enhanced-for loop of collections that needs scalar replacement of
> Iterator objects); I want to see benchmarks that show a well-representative
> assorting of lambda code, demonstrating that the optimizer will typically
> eliminate extra allocation imposed by the 'new'.
>
> [EA & stack allocation is already available; and we don't need a working
> prototype of a compiler for the lambda proposal as it's possible to manually
> write the same desugared code that would be emitted by such compiler. So,
> whoever believes in the lemma "let's make a mess - the JIT will clean up
> after us") must only write some benchmark code.]
>
> P.S.: EA & stack allocation are coming back in JDK 6u20, which is now in
> beta and is planned to ship on June. It seems that EA is in enough good
> shape as they're enabling it by default. OTOH, it's still exclusive to
> HotSpot Server, and I have little hope that the Client compiler will get
> this optimization any time soon. So I reinforce my negative vote (FWIW) on
> any important language design that will be good only for server-side apps -
> lambdas is a proposal for the next JavaSE platform, not for the next JavaEE
> platform.
>
> A+
> Osvaldo
>
> 2010/3/29 Peter Levart <peter.levart at marand.si>
>
> On 03/29/10, Howard Lovatt wrote:
>> > Just a note. I wouldn't suggest escape analysis as the appropriate
>> > optimization. It would need to be a new optimization.
>> >
>>
>> Do you have any idea how such optimization should work?
>>
>> Regards, Peter
>>
>>
>


-- 
 -- Howard.