[Rd] Should R Packages Unload Dynamic Libraries When They Unload?
From Hadley's C best practices
(http://r-pkgs.had.co.nz/src.html#c-best-practices):
> Like with C++, whenever you use C code in your package, you should unload the
> DLL when the package is unloaded:
.onUnload <- function (libpath) {
library.dynam.unload("mypackage", libpath)
}
Writing R Extensions on the other hand doesn't even mention this (AFAIK). I can
see how it would be polite to unload the dlls, but doing so seems to cause some
weird problems for me with packages that are loaded/unloaded/reloaded.
Additionally, there are some mentions that suggest maybe unloading isn't
required. From ?library.dynam:
> Note that whether or not it is possible to unload a DLL and then reload a
> revised version of the same file is OS-dependent: see the ‘Value’ section of
> the help for dyn.unload.
though this shouldn't affect objects that are not modified. Then there is this
comment from Brian Ripley in R-devel
(https://stat.ethz.ch/pipermail/r-devel/2010-November/059062.html):
> Having said all that, my experience is that unloading the DLL often does not
> help if you need to load it again (and that is why e.g. tcltk does not unload
> its DLL).
Is it acceptable for packages to leave the C libraries loaded when they are
unloaded?
I'm on R 3.1.1 on a Mac OS X, though this question is not specific to my system.
I originally asked this on SO
(http://stackoverflow.com/questions/26691878/must-r-packages-unload-dynamic-libraries-when-they-unload),
but got crickets.
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[Rd] segfault with readDCF on R 3.1.2 on AIX 6.1 when using install.packages
Dear list (re-posting from r-help as r-devel is probably more appropriate),
I was able to successfully compile R on our AIX box at work using the
GNU compilers following the instructions on the R Administration
guide. The output can be seen at here
(https://gist.github.com/nguyenvinh/504321ea9c89d8919bef) and yields
no errors .
However, I get a segfault whenever I try to use the install.packages
function to install packages. Using debug, I was able to trace it to
the readDCF function:
Browse[2]>
debug: if (!all) return(.Internal(readDCF(file, fields, keep.white)))
Browse[2]>
debug: return(.Internal(readDCF(file, fields, keep.white)))
Browse[2]>
*** caught segfault ***
address 4, cause 'invalid permissions'
Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
Selection:
Was curious if anyone has a clue on why such error exists or what I
could do to fix it? I'm able to install packages via R CMD INSTALL,
but I would hate to have to manually determine dependencies, download
the source for each package, and install them "by hand" via R CMD
INSTALL.
I went back and compiled older versions of R to see if this error
exists. On R 3.0.3, I get:
debug(available.packages)
install.packages('ggplot2', dep=TRUE, repo='http://cran.stat.ucla.edu')
...
Browse[2]>
debug: z <- res0 <- tryCatch(read.dcf(file = tmpf), error = identity)
Browse[2]>
Error: segfault from C stack overflow
On R 2.15.3, I do not see the error.
Would be great to get this resolved. Thank you for your help.
-- Vinh
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