[BUG][cryo] Create file on restart ?

[Serge E. Hallyn]

Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
> Serge E. Hallyn [serue at us.ibm.com] wrote:
> | Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
> | > Serge E. Hallyn [serue at us.ibm.com] wrote:
> | > | Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
> | > | > 
> | > | > cryo does not (cannot ?) recreate files if the application created
> | > | 
> | > | I think that's for the best.
> | > | 
> | > | Don't you?
> | > 
> | > I can understand that configuration or data files should exist, but
> | > not sure about temporary or log files that an application created
> | > upon start-up and expects to be present. Should the admin find
> | > out about them and create them by hand before restart ?
> | 
> | I think the admin should have set the destination environment such that
> | the task is restarted in the same network fs in the same directory, with
> | no files having been deleted.
> 
> or new files created ? For instance if the application was checkpointed
> before it created a temporary file with O_EXCL flag, that temporary
> file must not exist when restarting ?
> 
> | 
> | Am I wrong?
> 
> So we take a snapshot of the FS and checkpoint the application. Do they
> need to be atomic ? 
> 
> Eitherway, I withdraw the bug :-)

Well it's certainly beyond the scope of cryo.  I'd prefer if we didn't
have to snapshot the fs at each checkpoint (!) and I think any many or
most cases (think one long-running scientific app or seti at home that just
occasionally gets migrated or stopped for a reboot) it won't be an
issue.  But your point seems valid.

-serge