Struct/value types + stack allocations

[Kirk Pepperdine]

Hi Vitaly,

Sorry, but I'm still not seeing a use case for this. What is it that you're trying to do that you can't accomplish with a class? 

Oracle finally released invokedynamic after a lot of discussion but only after a number of people from both in and out side of Sun/Oracle  made significant efforts to make it happen. it's hard to get changes like this into the JVM and IMHO, it should/needs to be because OpenJDK  shouldn't shouldn't become a grab bag of everything that's cool new and shiny. Instead there is a conservative yet responsible path to innovation and it is that path that the invokedynamic people took. Same story with closures. Not quite the same story with generics and so....

Regards,
Kirk

On 2012-01-19, at 5:41 AM, Vitaly Davidovich wrote:

> Hi John,
> 
> Sorry, let me clarify - I'm not saying that this is a priority for me in the sense that it's preventing me from accomplishing something concrete.  Rather, it's something that I (and I think a substantial populace of other java developers) would really like to see in java and the VM.  I'm not sure how projects are selected for implementation by Oracle (e.g. how did invokedynamic, which is mostly useful for dynamic languages and not java, get Oracle engineers allocated to it? Did someone external contribute a preliminary prototype first?) but I was hoping that I could make a decent case for why something like this would be very welcomed by the java community and why I think it should get *relative* priority to other projects under consideration.
> 
> Feel free to move this conversation to mlvm (or something else) as it's getting a bit exploratory.
> 
> Thanks
> 
> Sent from my phone
> 
> On Jan 18, 2012 8:59 PM, "John Pampuch" <john.pampuch at oracle.com> wrote:
> Vitaly-
> 
> I think contributing to OpenJDK is the best way to express your priorities :)
> 
> The Java language probably wouldn't have constructs in it that could leverage a mechanism like this for a long time (if ever).  Would you mind sharing why this is a priority for you? 
> 
> -John
> 
> On 1/18/12 4:39 PM, Vitaly Davidovich wrote:
>> 
>> I also see my phone auto-corrected as heal instead of heel ... :)
>> 
>> To John, albeit selfishly :), I'd love to see structs prioritized over fixnums and maybe some of the other things (reification would be great too and would go a long way in reducing bloat due to boxed numerics).  Is there something akin to public voting on prioritization of features that Oracle agrees to dedicate resources to? Maybe I'm overestimating demand, but I think structs would get a lot of backing.
>> 
>> Thanks
>> 
>> Sent from my phone
>> 
>> On Jan 18, 2012 5:01 PM, "Ismael Juma" <mlists at juma.me.uk> wrote:
>> Hi all,
>> 
>> Vitaly Davidovich <vitalyd at ...> writes:
>> > The reason I ask is because I think the achilles heal of java performance
>> > is the memory consumption (this is something you often hear in discussions
>> > about java performance).
>> 
>> Agreed. I've seen and written tons of code to workaround the fact that there are
>> no structs in the language. Examples of popular open-source projects that use
>> parallel arrays (with much worse cache locality) to avoid objects and their
>> memory overhead are many (Lucene, Mahout, fastutil, Trove, JGit, etc.).
>> 
>> Best,
>> Ismael
>> 

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