[Rd] tempdir() may be deleted during long-running R session

[William Dunlap]

The Ubuntu machine I use a lot (along with others) must not be cleaning
/tmp as it has a fair number of Rtmp* directories in /tmp, even when there
are no R sessions running on the machine.  I would like to automate their
removal but there is no obvious way to see if the R process that created
the tempdir is still around.   If there were a way to associate R tempdir's
with R processes then one could make an R-specific tool to get rid of the
unused tempdirs.


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Wed, Apr 26, 2017 at 8:09 AM, Martin Maechler <maechler at stat.math.ethz.ch
> wrote:

> >>>>> Dirk Eddelbuettel <edd at debian.org>
> >>>>>     on Wed, 26 Apr 2017 08:40:38 -0500 writes:
>
>     > On 26 April 2017 at 08:29, Duncan Murdoch wrote:
>     > | This seems like the wrong approach.  The problem occurs as soon as
> the
>     > | tempdir() gets cleaned up:  there could be information in temp
> files
>     > | that gets lost at that point.  So the solution should be to
> prevent the
>     > | cleanup, not to continue on after it has occurred (as "check =
> TRUE"
>     > | does).  This follows the principle that it's better for the
> process to
>     > | always die than to sometimes silently produce incorrect results.
>
>     > That is generally true, but also "hard" as we don't have a handle on
> the OS
> .
>
> Indeed...
> and that was the reason I've proposed the simple platform
> agnostic tool which does not entirely solve the problem (in this sense I
> agree with "wrong approach") but allows to mitigate it and (by
> followup changes) to work around many use case problems.
>
>     > | Frederick posted the way to do this in systems using systemd.  We
> should
>
>     > While that was a very helpful post yet it may only apply to Arch
> Linux as
>     > stated.  My Ubuntu systems at home and work all run systemd too, but
> do _not_
>     > automatically remove tempfiles.
>
>     > Yet what he suggested is quite right: we should define a proper
> config file
>     > for this facility and then possibly also use the /run directory as
> many other
>     > services now and (of course) also either TEMPDIR or later the code
> to have
>     > /run be another fallback if TMP, TEMP, TMPDIR, ... are unset.
>
>     > Distribution maintainers such as yours truly could then include this
>     > configuration.
>
>     > | be putting that in place, or the equivalent on systems using other
>     > | tempfile cleanups.  This looks to me like something that "make
> install"
>     > | should do, or perhaps it should be done by people putting together
>     > | packages for specific systems.
>
>     > Doesn't 'make install' only write to $RHOME/ and below, plus
> $PREFIX/bin ?
>
> Also, 'make install' is optional for good reasons.
> E.g., I never ever run 'make install': I typically always have many R
> versions, all available in the shell and ESS (Emacs Speaks
> Statistics) via symbolic links into a directory on PATH.
>
> Dirk mentioned (as well) that this is all very platform specific
> which I do think is important. From my typical OS point of view:
>   Why should the user who runs R not have the right to delete the
>   tempdir which was created by the process that she runs and hence owns ?
>
> I agree it would be an improvement if we made such deletion much
> harder than it is now, and yes, there may be great (almost)
> cross-platform tools available to manage this much better than
> we do now, e.g., via open files.
>
> Before we are there, I would find it useful to have a new
> 'tempdir' (i.e. folder/directory for R's temporary files) to be
> re-created manually or automagically in those cases it has
> disappeared, and that is within easy reach via the proposed
> tempdir() functionality.
>
> OTOH, I typically live very well by quickly killing
> and restarting R (from inside ESS).
>
> The OP issue was to help newbies and computer-non-experts, the
> latter nowadays comprising more than 90% of R users (I'd guess ~
> 98% looking at our otherwise smart students).
>
> These are typically "slightly" confused when they ask for help and
> get a pretty severe error message:
>
>   > ?lm
>   Error in file(out, "wt") : cannot open the connection
>   In addition: Warning message:
>   In file(out, "wt") :
>     cannot open file '/tmp/RtmpztK6f7/Rtxt36972b91938': No such file or
> directory
>
>
> Martin
>
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