Re: Garbage Collector Cost

[Stefan Marr <lua@...>]

Metronome is supposed to be a hard real time GC for Java:
http://queue.acm.org/detail.cfm?id=1217268

http://www.research.ibm.com/vee04/Bacon.pdf

Perhaps that is relevant in this context...

Best regards
Stefan


On 27 Oct 2010, at 11:37, Paul Hudson wrote:

> Every hard real time system has some latency. It depends on the
> requirement if it works for your situation. If it has an upper bound
> it is hard real time in my view
> 
> On 27/10/2010, Rob Kendrick <rjek@rjek.com> wrote:
>> On Wed, Oct 27, 2010 at 12:10:35PM +0300, Juris Kalnins wrote:
>>> On Wed, 27 Oct 2010 11:58:16 +0300, Rob Kendrick <rjek@rjek.com> wrote:
>>> 
>>>> On Wed, Oct 27, 2010 at 08:39:58AM +0300, Juris Kalnins wrote:
>>>> 
>>>>> If the script is short lived, and turning GC completely off is
>>>>> an acceptable option, it's the most predictable way. It is
>>>>> possible then to
>>>>> run full GC manually at known times.
>>>> 
>>>> How is it possible to know how long the GC will take, even if you run it
>>>> at known times?
>>> 
>>> If you know how much allocated data there is, and you know that collection
>>> will not be delayed (e.g. because of __gc finalizers), then you have a
>>> known upper bound on mark&sweep time.
>> 
>> And what if this upper-limit on time is greater than your hard real-time
>> will allow?  ie, you get a break in your work, so you decide to do some
>> GC, but it's going to take longer than you have time available before
>> you need to do work again.  What do you do?  Put it off until next time?
>> What if the same happens again?
>> 
>> Basically, the only solutions are infinite memory (turn off GC) or a
>> very fruity GC system using content-addressable memory (which nobody
>> has.)
>> 
>> B.
>> 
>> 
> 
> -- 
> Sent from my mobile device
> 

-- 
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
http://soft.vub.ac.be/~smarr
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