I have found some weird SEXP corruption behavior with ALTREP, which
could be a bug. (Or I could be doing something wrong.)
I have an integer ALTREP vector that calls back to R from the Elt
method. When this vector is indexed in a lapply(), its first element
gets corrupted. Sometimes it's just a type change to logical, but
sometimes the corruption causes a crash.
I saw this on macOS from R 3.5.3 to 4.2.0. I created a small package
that demonstrates this: https://github.com/gaborcsardi/redfish
The R callback in this package calls `loadNamespace("Matrix")`, but
the same crash happens for other packages as well, and sometimes it
also happens if I don't load any packages at all. (But that example
was much more complicated, so I went with the package loading.)
It is somewhat random, and sometimes turning off the JIT avoids the
crash, but not always.
Hopefully I am just doing something wrong in the ALTREP code (see
https://github.com/gaborcsardi/redfish/blob/main/src/test.c), and it
is not actually a bug.
Thanks,
Gabor
iuke-tier@ey m@iii@g oii uiow@@edu
2021-May-28 13:41 UTC
[Rd] [External] Possible ALTREP bug
integer and real Elt methods are not expected to allocate. You would have to suspend GC to be able to do that. This currently can't be done from package code. Best, luke On Fri, 28 May 2021, G?bor Cs?rdi wrote:> I have found some weird SEXP corruption behavior with ALTREP, which > could be a bug. (Or I could be doing something wrong.) > > I have an integer ALTREP vector that calls back to R from the Elt > method. When this vector is indexed in a lapply(), its first element > gets corrupted. Sometimes it's just a type change to logical, but > sometimes the corruption causes a crash. > > I saw this on macOS from R 3.5.3 to 4.2.0. I created a small package > that demonstrates this: https://github.com/gaborcsardi/redfish > > The R callback in this package calls `loadNamespace("Matrix")`, but > the same crash happens for other packages as well, and sometimes it > also happens if I don't load any packages at all. (But that example > was much more complicated, so I went with the package loading.) > > It is somewhat random, and sometimes turning off the JIT avoids the > crash, but not always. > > Hopefully I am just doing something wrong in the ALTREP code (see > https://github.com/gaborcsardi/redfish/blob/main/src/test.c), and it > is not actually a bug. > > Thanks, > Gabor > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >-- Luke Tierney Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: luke-tierney at uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
Hi Gabor, Calling back to an R function from the ALTREP function is not safe. There has been a heated discussion on why you should not do it and that the main reason that we do not have any R level ALTREP API. If you are interested in it you can find it from this issue: https://github.com/Bioconductor/Contributions/issues/1222 Best, Jiefei On Fri, May 28, 2021 at 4:54 PM G?bor Cs?rdi <csardi.gabor at gmail.com> wrote:> > I have found some weird SEXP corruption behavior with ALTREP, which > could be a bug. (Or I could be doing something wrong.) > > I have an integer ALTREP vector that calls back to R from the Elt > method. When this vector is indexed in a lapply(), its first element > gets corrupted. Sometimes it's just a type change to logical, but > sometimes the corruption causes a crash. > > I saw this on macOS from R 3.5.3 to 4.2.0. I created a small package > that demonstrates this: https://github.com/gaborcsardi/redfish > > The R callback in this package calls `loadNamespace("Matrix")`, but > the same crash happens for other packages as well, and sometimes it > also happens if I don't load any packages at all. (But that example > was much more complicated, so I went with the package loading.) > > It is somewhat random, and sometimes turning off the JIT avoids the > crash, but not always. > > Hopefully I am just doing something wrong in the ALTREP code (see > https://github.com/gaborcsardi/redfish/blob/main/src/test.c), and it > is not actually a bug. > > Thanks, > Gabor > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel