>>>>> Ivan Krylov
>>>>> on Tue, 2 May 2023 14:59:36 +0300 writes:
> ? Sat, 29 Apr 2023 00:00:02 +0000
> Dario Strbenac via R-devel <r-devel at r-project.org> ?????:
>> Could save.image() be redesigned so that it promptly responds to
>> Ctrl+C? It prevents the command line from being used for a number
of
>> hours if the contents of the workspace are large.
> This is ultimately caused by serialize() being non-interruptible. A
> relatively simple way to hang an R session for a long-ish time would
> therefore be:
> f <- xzfile(nullfile(), 'a+b')
> x <- rep(0, 1e9) # approx. 8 gigabytes, adjust for your RAM size
> serialize(x, f)
> close(f)
> This means that calling R_CheckUserInterrupt() between saving
> individual objects is not enough: R also needs to check for interrupts
> while saving sufficiently long vectors.
> Since the serialize() infrastructure is carefully written to avoid
> resource leaks on allocation failures, it looks relatively safe to
> liberally sprinkle R_CheckUserInterrupt() where it makes sense to do
> so, i.e. once per WriteItem() (which calls itself recursively and
> non-recursively) and once per every downstream for loop iteration.
> Valgrind doesn't show any new leaks if I apply the patch, interrupt
> serialize() and then exit. R also passes make check after the applied
> patch.
> Do these changes make sense, or am I overlooking some other problem?
Thank you, Ivan!
They do make sense... but :
OTOH, in the past we have had to *disable* R_CheckUserInterrupt()
in parts of R's code because it was too expensive,
{see current src/main/{seq.c,unique.c} for a series of commented-out
R_CheckUserInterrupt() for such speed-loss reasons}
so adding these may need a lot of care when we simultaneously
want to remain efficient for "morally valid" use of serialization...
where we really don't want to pay too much of a premium.
{{ saving the whole user workspace is not "valid" in that sense
in my view. I tell all my (non-beginner) Rstudio-using
students they should turn *off* the automatic saving and
loading at session end / beginning; and for reproducibility
only saveRDS() [or save()] *explicitly* a few precious
objects ..
}}
Again, we don't want to punish people who know what they are
doing, just because other R users manage to hang their R session
by too little thinking ...
Your patch adds 15 such interrupt checking calls which may
really be too much -- I'm not claiming they are: with our
recursive objects it's surely not very easy to determine the
"minimally necessary" such calls.
In addition, we may still consider adding an extra optional
argument, say `check.interrupt = TRUE`
which we may default to TRUE when save.image() is called
but e.g., not when serialize() is called..
Martin
> --
> Best regards,
> Ivan
> x[DELETED ATTACHMENT external: Rd_IvanKrylov_interrupt-serialize.patch,
text/x-patch]
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