[Rd] Fw: alpha transparency crashes R

[Paul Murrell]

Hi


Deepayan Sarkar wrote:
> I'm forwarding a bug report from Jeff Gove that didn't make it to the list.
> -Deepayan
> 
> ------- Original Message --------
> Subject: 	alpha transparency crashes R
> Date: 	Fri, 07 Nov 2008 14:32:27 -0500
> From: 	jeff gove <jhgove at unh.edu>
> To: 	r-bugs at r-project.org
> 
> 
> I ran into a problem with R crashing when a certain number of
> transparent objects (e.g., symbols) are sent to a PDF output device.
> This has happened on R 2.71, 2.7.2 (Fedora 8 and Ububtu 8.04
> platforms) and now 2.8.0 (I've only tried Fedora 8). The current
> pertinent R system stats are...
> 
> R.version
>                _
> platform       x86_64-redhat-linux-gnu
> arch           x86_64
> os             linux-gnu
> system         x86_64, linux-gnu
> status
> major          2
> minor          8.0
> year           2008
> month          10
> day            20
> svn rev        46754
> language       R
> version.string R version 2.8.0 (2008-10-20)
> 
> The following small example program when run with n large enough
> (e.g., n=1000) and transparency will crash R...
> 
> alphaBomb.r = function(n=100, wantAlpha=T) {
>    df = data.frame(a=rnorm(n),b=runif(n))
>    if(wantAlpha)
>      alpha=runif(n)
>    else
>      alpha = 1
>    j = xyplot(b~a, df, alpha=alpha, pch=19)
>    print(j)
>    trellis.device('pdf',file='alphaBomb.pdf',version='1.4')
>    print(j)
>    dev.off()
> }
> 
> Please note that the crash seems to occur in the dev.off() component,
> and that the file actually seems to get written out correctly.  The
> trace of the bomb is found below, excluding the memory map. Please
> also note that it may be somehow related to grid, as the following
> code (supplied by Deepayan Sarkar) using base graphics does not crash
> R, even with n=100000...
> 
> pdf()
> n = 1000
> plot(rnorm(n), rnorm(n), col = rgb(0, 0, 0, alpha = runif(n)), pch = 16)
> dev.off()


Grid runs laughing from your puny accusations!
This will tickle the problem too:

plot(rnorm(n), rnorm(n), col = rgb(0, 0, 0, alpha = runif(n)), pch = 19)

The issue appears to be in the PDF device driver, which has a fixed-size
integer array called pd->pos and those larger examples are generating
"too many" different alpha values so that we end up assigning values
out-of-range for that array.

The simple fix is to bump up the initial size of the pd->pos array, but
there is some heuristic code in devPS.c (PDF_NewPage) that appears to be
trying to resize the array on-the-fly based on how many pages are being
generated, so perhaps this needs a bit more thought.

Thanks for the bug report!

Paul


> The error trace from the above alphaBomb.r() code is...
> 
> R> alphaBomb.r(100)   #this is fine
> X11cairo
>        2
> 
> R> alphaBomb.r(1000,F) #also fine
> 
> R> alphaBomb.r(1000)
> *** glibc detected *** /usr/lib64/R/bin/exec/R: double free or
> corruption (!prev): 0x00000000032c1d90 ***
> ======= Backtrace: =========
> /lib64/libc.so.6[0x3ee8c72832]
> /lib64/libc.so.6(cfree+0x8c)[0x3ee8c75f2c]
> /usr/lib64/R/library/grDevices/libs/grDevices.so[0x2aaab000b0fc]
> /usr/lib64/R/lib/libR.so[0x3d1f48ddd3]
> /usr/lib64/R/lib/libR.so[0x3d1f48e2dc]
> /usr/lib64/R/lib/libR.so[0x3d1f4ec81c]
> /usr/lib64/R/lib/libR.so(Rf_eval+0x42e)[0x3d1f4be8ae]
> /usr/lib64/R/lib/libR.so[0x3d1f4bf572]
> /usr/lib64/R/lib/libR.so(Rf_eval+0x42e)[0x3d1f4be8ae]
> /usr/lib64/R/lib/libR.so(Rf_applyClosure+0x291)[0x3d1f4c0bf1]
> /usr/lib64/R/lib/libR.so(Rf_eval+0x303)[0x3d1f4be783]
> /usr/lib64/R/lib/libR.so[0x3d1f4bf572]
> /usr/lib64/R/lib/libR.so(Rf_eval+0x42e)[0x3d1f4be8ae]
> /usr/lib64/R/lib/libR.so(Rf_applyClosure+0x291)[0x3d1f4c0bf1]
> /usr/lib64/R/lib/libR.so(Rf_eval+0x303)[0x3d1f4be783]
> /usr/lib64/R/lib/libR.so(Rf_ReplIteration+0x188)[0x3d1f4dc878]
> /usr/lib64/R/lib/libR.so[0x3d1f4dcb90]
> /usr/lib64/R/lib/libR.so(run_Rmainloop+0x50)[0x3d1f4dcec0]
> /usr/lib64/R/bin/exec/R(main+0x1b)[0x40082b]
> /lib64/libc.so.6(__libc_start_main+0xf4)[0x3ee8c1e074]
> /usr/lib64/R/bin/exec/R[0x400729]
> ======= Memory map: ========
> etc...
> 
> Please note that R only crashes with PDF output; tiff, png and eps
> (even though it doesn't accept transparency) all exit cleanly.
> 
> My version of glibc is 2.7.
> 
> Thanks, I hope that the problem is already resolved!
> 
> Jeff
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/