[talk] Python

[Sujit K M]

On Thu, Apr 28, 2016 at 5:36 PM, Edward Capriolo <edlinuxguru at gmail.com> wrote:
> https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html

I still guess the classfile size on hard disk.

> http://www.javaworld.com/article/2077408/core-java/sizeof-for-java.html

No Size of In Java Is what I see in this document.

But let me take a guess, Every programmer has to calculate his object
size an then
see whether it is actually equal to file size on his disk. Or better
still add a commit hook
to check and do a basic primitive validation.

> On Thursday, April 28, 2016, Edward Capriolo <edlinuxguru at gmail.com> wrote:
>>
>> The java class file format is well documented. Basically one pointer to
>> the runtime class of the object followed by the object.
>>
>> If a given language is reference counted each object has one extra atomic
>> field to count references.
>>
>> If a given language does not have objects but instead uses maps (that
>> repeat the fields evey instance) that is going to be a more large object in
>> memory.
>>
>> While i am not a large expert in this i believe javas approach is like a c
>> struct with the exception the first word size bytes are a pointer to the
>> type of class so that instances can be runtime inspected.
>>
>> Java also has a very clever system for compressing 64 bit pointers.. see
>> compressedOOPs option. I have not heard much of this optimization anywhere
>> else.
>>
>> On Thursday, April 28, 2016, Sujit K M <kmsujit at gmail.com> wrote:
>>>
>>> > Anecdotal. Keep in mind I have tested this and you can create 'a lot
>>> > more
>>> > objects' given the same RAM than many other popular non java languages.
>>> > :)
>>>
>>> Could you please clarify further? I mean does it involve a object size
>>> on the JVM.
>>> How to measure the size occupied by the Object? How much extra space the
>>> JVM
>>> needs? What is JDK Feature that Let's you claim this?
>>>
>>> I have serious questions regarding this claim. As Interpreted or JIT
>>> compiled languages
>>> should in reality occupy more space.
>>>
>>> >
>>> > On Wed, Apr 27, 2016 at 4:13 PM, Pete Wright <pete at nomadlogic.org>
>>> > wrote:
>>> >>
>>> >>
>>> >>
>>> >> On 04/26/2016 03:56 AM, Brian Coca wrote:
>>> >>>
>>> >>> As many a Java dev has told me: "the only problem is that you did not
>>> >>> install enough RAM, just add it, it's cheap!"
>>> >>>
>>> >>>
>>> >>
>>> >> and therein is the issue - in practice i've found that by adding more
>>> >> memory to a JVM heap will tend to worsen GC pauses, especially for
>>> >> latency
>>> >> sensitive operations.  then you get to do all sorts of fun stuff like
>>> >> storing cached objects outside of the JVM or lord knows what.
>>> >>
>>> >> i spent about 3 months trying to help a team tune their java app when
>>> >> they
>>> >> noticed it would periodically show latencies of several seconds. they
>>> >> kept
>>> >> adding more memory to the heap, which made things worse.  once we
>>> >> turned on
>>> >> debugging metrics for GC it became painfully apparent that due to the
>>> >> huge
>>> >> heap that they had allocated GC was taking ages to complete and
>>> >> stopping to
>>> >> world in the process.  good times :)
>>> >>
>>> >> -pete
>>> >>
>>> >> --
>>> >> Pete Wright
>>> >> pete at nomadlogic.org
>>> >>
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>>> >
>>> >
>>> >
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>>
>>
>> --
>> Sorry this was sent from mobile. Will do less grammar and spell check than
>> usual.
>
>
>
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> Sorry this was sent from mobile. Will do less grammar and spell check than
> usual.