Limiting Memory Usage

Limiting Memory Usage

[Alexander Fuchs]

Hi,

I would like to:
- limit the max. memory usage of an ocaml program
- and do some cleanup and then terminate then program, when this limit
is reached.

I couldn't see how to do that with the standard libraries, so I added a
C-wrapper to use setrlimit with RLIMIT_AS. I guess that works only with
Linux, which is not nice but better than nothing.

Still, when the memory limit is reached the program just terminates with
"Fatal error: out of memory." resp "Out of memory". I couldn't figure
out if it is possible to catch any of those errors/exceptions, and do
some cleanup before terminating the program.

Does perhaps someone know how to provide this functionality in a more
satisfactory way?

Thanks,
	Alexander

Re: [Caml-list] Limiting Memory Usage

[Chris King]

On 7/13/06, Alexander Fuchs <alexander.fuchs@uni-koblenz.de> wrote:
> I would like to:
> - limit the max. memory usage of an ocaml program
> - and do some cleanup and then terminate then program, when this limit
> is reached.
>
> I couldn't see how to do that with the standard libraries,

Did you look at Gc?  It's not a hard limit but periodically checking
(quick_stat ()).heap_words will give you a rough estimate of how much
memory your program is using (not exact since it doesn't count
code/stack/etc.).

- Chris King

Re: [Caml-list] Limiting Memory Usage

[Alexander Fuchs]

Hi,

Chris King wrote:
 > Did you look at Gc?  It's not a hard limit but periodically checking
 > (quick_stat ()).heap_words will give you a rough estimate of how much
 > memory your program is using (not exact since it doesn't count
 > code/stack/etc.).

thanks for the suggestion. For some reason I thought that monitoring 
memory usage by calling the Gc functions often tends to be expensive.

But someone suggested to use Gc.create_alarm, and this works fine.

Thanks,

	Alexander

Re: [Caml-list] Limiting Memory Usage

[Damien Doligez]

On 2006-07-14, at 05:39, Alexander Fuchs wrote:

> Still, when the memory limit is reached the program just terminates  
> with
> "Fatal error: out of memory." resp "Out of memory". I couldn't figure
> out if it is possible to catch any of those errors/exceptions, and do
> some cleanup before terminating the program.

There is currently no way to catch these errors, because the heap
is in an inconsistent state when they are triggered.  This might
change at some point in the future, but don't hold your breath.

-- Damien