R devel - Feb 2005 - RData loading weirdness

I've just had an interesting thing happen to one of our students. He's 
using R 1.9.1 on Linux, and so I dont expect bugfixes, I'm just 
reporting this out of interest in case anyone else has had this happen.

  Starting R caused a seg fault shortly after "[Previously saved 
workspace restored]". Running "R --no-restore-data" worked fine
so I
suspected a corrupted .RData. It was 67M big, with about 400 objects - 
nothing extreme there. But then doing load(".RData") worked fine.
There
were his objects. How strange.

  I deleted the first 200 objects, saved the .RData, and retried. That 
worked, so I thought it might have been an object in the last 200 or so. 
So I saved them to .RData. Starting up with that worked.

  So, starting afresh with the original load(".RData"), I saved two 
.RData files with each part. Quit, start again, load("part1.RData")
and
load("part2.RData"), then quit and save. Now I had all 400-ish objects
in one .RData. Time to start R and see if it can startup with it.

  And it did. Worked fine. So I suspect a subtle bug in reading .RData 
files or subtle corruption in the .RData. Most odd. Oh well, I guess I 
could see what R 2.x.x does with it....

Barry

[Moved to R-devel: see the posting guide for the currently made 
distinction.]

The format of .RData has not changed, so this is still of interest.

We have seen things like this, the problem being the way an out-of-memory 
condition got handled by Linux -- how much memory did his machine have?
(Remember 67Mb is compressed, often highly compressed.)

It has certainly been possible to save a workspace that needs much more 
memory to be restored on the same machine than it originally took.

We've found Linux to be rather unhelpful with out-of-memory conditions: 
one of our servers started `randomly' killing processes when its swap 
space got full -- and one of the first was the sshd daemon which cut off 
all remote access ....

On Tue, 1 Feb 2005, Barry Rowlingson wrote:
>
> I've just had an interesting thing happen to one of our students.
He's using
> R 1.9.1 on Linux, and so I dont expect bugfixes, I'm just reporting
this out
> of interest in case anyone else has had this happen.
>
> Starting R caused a seg fault shortly after "[Previously saved
workspace
> restored]". Running "R --no-restore-data" worked fine so I
suspected a
> corrupted .RData. It was 67M big, with about 400 objects - nothing extreme 
> there. But then doing load(".RData") worked fine. There were his
objects. How
> strange.
>
> I deleted the first 200 objects, saved the .RData, and retried. That
worked,
> so I thought it might have been an object in the last 200 or so. So I saved
> them to .RData. Starting up with that worked.
>
> So, starting afresh with the original load(".RData"), I saved two
.RData
> files with each part. Quit, start again, load("part1.RData") and 
> load("part2.RData"), then quit and save. Now I had all 400-ish
objects in one
> .RData. Time to start R and see if it can startup with it.
>
> And it did. Worked fine. So I suspect a subtle bug in reading .RData files 
> or subtle corruption in the .RData. Most odd. Oh well, I guess I could see 
> what R 2.x.x does with it....
>
> Barry
>
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>
-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595