[erlang-questions] Cost of hibernation

[Pablo Polvorin]

Hello

On 22 July 2013 13:18, Valentin Micic <v@REDACTED> wrote:
> Thanks Pablo,
>
> Just want to confirm that when you say:
>
> "The time the processes where hibernated was in the range of seconds…"
>
> you mean that an average time between two messages addressing the same process can be measured in seconds?

yes, exactly.

>
> Kind reagards
>
> V/
>
>
> On 22 Jul 2013, at 5:26 PM, Pablo Polvorin wrote:
>
>> Hello,
>> On 22 July 2013 11:57, Valentin Micic <v@REDACTED> wrote:
>>> Dear all,
>>>
>>> Erlang reference manual makes a following statement regarding
>>> erlang:hibernate/3
>>>
>>> "erlang:hibernate(Module, Function, Args)
>>>
>>> Types:
>>>
>>> Module = Function = atom()
>>> Args = [term()]
>>>
>>> Puts the calling process into a wait state where its memory allocation has
>>> been reduced as much as possible, which is useful if the process does not
>>> expect to receive any messages in the near future.
>>>
>>> …"
>>>
>>> I have never used the hibernate function fearing that performance penalty to
>>> be paid may be to high.  In other words, I never really had to use it ;-)
>>>
>>> But now that I do, may I kindly ask if there is anyone out there that did
>>> successfully used this feature and has a clear idea regarding performance
>>> penalty.
>>> Would it be cheaper to store and retrieve a context using ETS (which would
>>> certainly complicate programming), or would a call to hibernate do the
>>> trick?
>>>
>>> Maybe another way to ask this question could be: what is the cost of calling
>>> a garbage collection frequently?
>>>
>>> Also, would anyone care to define a meaning of "the near future" within this
>>> context? Should one measure "the near future"  in milliseconds, seconds or
>>> minutes?
>> As vague as it is, maybe this helps:
>> I had used it in a few systems.  In tsung for example (with hundreds
>> of thousands of processes simulating user behavior),  there was a big
>> memory saving,  and the time the processes where hibernated was in the
>> range of seconds,  not minutes.    The difference in cpu usage in that
>> case was barely noticeable
>>
>>>
>>> Kind regards
>>>
>>> V/
>>>
>>> _______________________________________________
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>>>
>>
>>
>>
>> --
>> Pablo Polvorin
>> ProcessOne
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>



-- 
Pablo Polvorin
ProcessOne