🚀 go-pugleaf

Lori M Olson [TeamB] wrote:
> Vander wrote:
> 
>> I want to assess some implementation details, some which can be 
>> expected to be common among the major VM implemetatons (for default I
>>  am referring to the Win32 implementation).
>>
>> A good programmer is interested to know what he really invokes when 
>> allocating a new object. For example the minimum data size that an 
>> instance of a type consumes on the heap. Perhaps the question can be
>>  transformed into "what is the minimum size of data allocation blocks
>>  on the heap?". I have looked into the VM documents but found nothing
>>  about this because it is undefined. - So does somebody know about 
>> what the real practice is? Or where can I go to look for more 
>> information?
>>
>> Thanks! - Vander
> 
> 
> 1.  You really do not need to know this stuff, unless you are working
> with embedded systems.  And if you are working with embedded systems,
> then you would have all the documentation you needed already.
> 
> 2.  But, if you insist, there are lots of tools to help you profile your
> application.  If you are using Developer or Enterprise edition, you will
> already have a built-in copy of OptimizeIt, so I suggest you use that.
> If you are using Foundation, you will want to check out some freebies.
> I found this page which is only 6 months old, so it should be up to date:
> 
> http://www.manageability.org/blog/stuff/open-source-profilers-for-java/view
> 
> Last, but not least, let me inflict MHO on you... DON'T optimize for the
> sake of optimizing.  Define some reasonable metrics, figure out how to
> test against those metrics, and then DON'T bother optimizing until those
> tests start to fail.  Otherwise you'll just be screwing around wasting a
> bunch of time.
> 

I don't think I'm wasting time if I want to know what the minimum object 
size is, as a background information to decide on algorithmic 
alternatives. But thanks for the hint, perhaps I'm on the right track there.

Btw, I wonder what makes people so blindly proud about the Java memory 
management. The system has a rather dangerous memory consumption and not 
rare an application gets problems with the out-of-memory message. Just a 
side-note!

- Vander