[Carpet] checkpoint at run-time request

[Erik Schnetter]

On Oct 18, 2006, at 09:15:59, Bela Szilagyi wrote:

> Every once in a while (e.g., five minutes ago) I find myself guilty  
> of not
> having requested checkpoint files at a large enough frequency.
>
> In other terms, my current run may die before getting to its first  
> check-point
> file.  It will check-point at termination, but this data may not be  
> good for
> restarting another run with a "fix".
>
> The question comes -- would it be possible to add some feature that  
> would
> allow me to tell a running simulation -- "please dump a checkpoint,  
> then go
> on."  The ordinary solution would be having Cactus watch a file in  
> which the
> user can place the request...  I know there is the web-interface  
> option of
> steering parameters, but I never trusted that enough to try...
>
> Could one just send a signal of some sort to the running code and  
> have the
> checkpoint file be dumped?
>
> More generically, it would be quite useful to have a simple,  
> usable, and
> trustworthy way of modifying parameters of a run, while it's  
> running.  Say,
> again, a simple ascii file being watched, read, parsed at every so  
> many
> iterations...

Cactus has a web server thorn.  This thorn allows steering  
parameters.  There is a parameter "checkpoint_next", which writes a  
checkpoint in the next iteration.  You can also steer the parameters  
for checkpoint_every, out_every, etc.  You can change which variables  
are output, how verbose the screen output should be.  You can also  
terminate the simulation.

The web server thorn also lets you look at variables which are not  
output to disk.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>

My email is as private as my paper mail.  I therefore support encrypting
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