[GRASS5] Re: [GRASSLIST:4564] Re: .tmp files

[Markus Neteler]

On Tue, Sep 24, 2002 at 03:53:30PM +0200, Roger Bivand wrote:
> On Tue, 24 Sep 2002, Markus Neteler wrote:
> 
> > (moving this to the developers list)
> > 
> > On Tue, Sep 24, 2002 at 03:01:45AM +0100, Glynn Clements wrote:
> > > 
> > > Gordon Keith wrote:
> > > 
> > > > > The ".tmp" directory should get cleaned whenever you exit a GRASS
> > > > > session.
> > > > >
> > > > > If your ".tmp" directories are accumulating files, that suggests that
> > > > > GRASS sessions are being terminated abnormally, e.g. by killing the
> > > > > xterm. Always terminate the session by typing "exit" in the shell.
> > > > 
> > > > OK.
> > > > 
> > > > It's probably my fault then.
> > > > 
> > > > I've been using g.gisenv set= to swap better mapsets and locations a lot 
> > > > rather than having to exit and restart grass several times a day. I 
> > > > guess this is one of the gotchas of doing that.
> > > 
> > > OK; yes, the other reason why temporary files may accumulate is if you
> > > have long-running sessions. Until recently this seldom happened, as
> > > you had to quit in order to change the location or mapset.
> > 
> > Well, this happens regularly (at least for our group).
> > We work in one location only, so there is no obvious reason
> > to leave the location. Then the .tmp/ stuff accumulates quickly.
> > 
> > One problem is that some GRASS modules open temp files with
> > G_tempfile() but do not remove them on exit.
> > We were talking about that also in May:
> > 
> > http://grass.itc.it/pipermail/grass5/2002-May/002978.html
> > 
> > > Either terminate the session at the end of the day, or manually run
> > > $GISBASE/etc/clean_temp occasionally. Unfortunately, this can't be
> > > automated, as a few programs expect temporary files to survive for a
> > > while after the program which created them has terminated.
> > >
> > > Mostly this is due to either:
> > > 
> > > a) a program creating a temporary file, then running some other
> > > program with that temporary file as input.
> > > 
> > > b) d.text, which saves its input in a temporary file; this file needs
> > > to remain until the monitor is erased, as it will be used if the
> > > monitor needs to be redrawn (either via d.resize/d.redraw or, for
> > > XDRIVER, if the monitor is resized via the window manager).
> > > 
> > > Apart from that, I suspect that a lot of programs need to take more
> > > care to remove temporary files once they are no longer needed.
> > 
> > Yes.
> > 
> > Another suggestion may be a GRASS daemon which get's informed about
> > temp files and can delete them later (rather than the  simplistic 
> > clean_temp approach). We should probably centralize such management
> > functionality.
> > 
> > Roger, does your GRASS daemon have such capabilities (or potential to
> > be extended?).
> > 
> No daemon around yet ...

sorry, I was thinking of Roger Miller's daemon.

> What about a cron job - FAQ entry to suggest to people to have cron clear 
> up their temp files. Do we know which ones need to be protected from 
> removal - this is also info a daemon might need?

exactly. We need a tool to distinguish between temp-in-use and oldish
temp files. That's why they may be registered at the daemon. The daemon
can watch processes running and check if they terminated/got killed.

Only the d.text problem cannot be solved like that (or the temp file
registrations needs extended information not to delete certain temp
files).

Markus