On 12-10-30 11:13 PM, Adam Clark wrote:
I'm running R 2.15.1x64, though the same problem persists for 2.13.0x32 and
2.13.0x64.
I am trying to run compiled C code using the .C convention. The
code compiles without problems, dynamically loads within the R
workspace with no problems, and even runs and gives correct results with
no problems.
However, R will randomly crash within a few minutes of successfully using
the compiled function.
For example, if I run my compiled function using:
dyn.load("mycfun.dll")
answer<-.C("mycfun", parameters...), I get a completely sensible
result that gets stored to "answer".
However, if I try to do too many things to "answer", the R exits
without warning.
I've tried dyn.unload in hopes that R would become stable afterwards, but
in this case using the function crashes R without fail.
Usually, I can either plot, or view, or save "answer" to a file - but never
take more than a single action before R exits. This does not appear to
depend on how long R has been open. Initially, I thought it was a bug in
the "inline" function, but I'm finding the same problem now that I'm using
the dynamically loaded file directly. I'm used to R being insanely stable,
and am somewhat mystified by this whole problem.
My next move is to learn the ".Call" convention, as I suspect that
my problem is related to my "C" function using memory that R doesn't
know is used. But - before I invest a while lot more time on this, I'd
like to know whether anybody things this is likely to solve the problem.
If not, I may just want to run my code entirely in C, and forget the
R problem.
I think your C code has a bug in it. The bug might go away when you
rewrite the function to work within the .Call convention, but it is
probably easier to find the bug and fix it with the current code.
Things to look for:
Are you fully allocating all arrays in R before passing them to C? The
C code receives a pointer and will happily write to it, whether that
makes sense or not.
Are you careful with your limits on vectors? In R, a vector is indexed
from 1 to n, but the same vector in C is indexed from 0 to n-1. If the
C code writes to entry n, that will eventually cause problems.
Are you allocating memory in your C code? There are several ways to do
that, depending on how you want it managed. If you do it one way and
expect it to be managed in a different way, you'll get problems.
Duncan Murdoch
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