R devel - Jun 2011 - Ctrl-C of functions that allocated mem

Hello,


what happens, when a function (R-extension in C), that allocated memory
(strdup(), malloc()/calloc() and so on), and is used in interactive mode, then
will be stopped via Ctrl-C?

I would assume that there remains allocated memory,
which is not usable and also not accessable (hence no
way to free it).

Are there any mechanisms in R that could help in rolling
back the allocation?

Normally in an interactive session "some memory" might not be a
problem,
because it will be run shortly; but I prefer clean solutions.
And also, if it's much mem, which is allocated each time, and one does many
trials and Ctr-C's, even an interactive session might eat a lot of mem.

So I would be interested in a solution to this (potential) problem.


Ciao,
   Oliver

On Jun 8, 2011, at 8:06 PM, oliver wrote:
> 
> Hello,
> 
> 
> what happens, when a function (R-extension in C), that allocated memory
> (strdup(), malloc()/calloc() and so on), and is used in interactive mode,
then
> will be stopped via Ctrl-C?
> 
> I would assume that there remains allocated memory,
> which is not usable and also not accessable (hence no
> way to free it).
> 
> Are there any mechanisms in R that could help in rolling
> back the allocation?
> 
Yes, if you read R-exts:
http://r.research.att.com/man/R-exts.html#Memory-allocation
you would know that you're not supposed to use malloc/calloc at all and if
you allow interruption ("regular" C code does not) R_alloc does what
you asked about.

Cheers,
Simon

> Normally in an interactive session "some memory" might not be a
problem,
> because it will be run shortly; but I prefer clean solutions.
> And also, if it's much mem, which is allocated each time, and one does
many
> trials and Ctr-C's, even an interactive session might eat a lot of mem.
> 
> So I would be interested in a solution to this (potential) problem.
> 
> 
> Ciao,
>   Oliver
> 
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> 
>