[R] What is the meaning of "segfault 'memory not mapped' " ?

[Ben Bolker]

Ubuntu.Diego <ubuntu.diego <at> gmail.com> writes:

> 
> I'm trying to get some "easy coding" to reproduce the error. In the
> meantime I have R code that run for 20 or more hours and suddenly i got
> a "segfault 'memory not mapped'" error. I have to clarify that the error
> not alway occurs and sometimes the process end satisfactorily. The
> process is basically a search using an MCMC strategy, sometimes the
> algorithm converge and stops others I got the error message. I was
> wondering if it could be meaning that I run out of RAM.
> Thanks
> 
> PS: I don't want to submit code that maybe after 48 hours of running
> still don't generate the error.
> 

  that makes sense ...

  We need more information about what you are trying to do,
what packages you're using, etc..  In general a segfault means
a bug -- in R if the functions you're using are base R, but
more likely in C code that you wrote or that comes from
a contributed package (since the C code in R has been
pretty thoroughly hammered on, it's much less likely -- although
not impossible -- that it contains a memory bug like this).
If you're using C code you wrote yourself, it's almost
certainly in there.

  Can you tell us what functions you were using,
results of sessionInfo, etc. ?

  If it's your own code or if you're feeling adventurous
you can try to use valgrind to locate the problem --
see

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/124215.html

for a start, or the R Extensions manual ...

  Ben Bolker