[R] Is R multi-threaded?

[flyfish72@fastmail.fm]

Hi,

I couldn't find a good answer for this anywhere in the docs, and I've
looked through the code for 1.8.0;  could someone who knows please
confirm that R (for unix) is *not* currently multi-threaded?

(I'm having trouble dynamically loading a C++ shared lib, and I want to
make sure it's not thread-related)

Thanks,
Annie