This means that the threaded approach is useless.

Hm. I'm not sure that is true.

It's unclear to me from the 3 posts in that thread whether they are talking about talking to multiple processes from different threads--as you are trying to do--or whether they are talking about talking to R.dll from multiple threads when embeding R in a C/C++ program.

At one point the OP talks of "calling R", at another "the R process". And most of the "threads" discussion by the 2 experts seems to be talking about threading R internally--ie. within a single R process--rather than having two process instances running concurrently.

I remember many of the dlls in OS/2 v1.x were inherently thread-unsafe, mostly because they were written in C by ex-COBOL programmers who hadn't quite gotten over the 'static data section' way of thinking. But I didn't think anyone still coding for a living was still doing stuff like that.

By far the simplest way of verifying this would be run something in each of two concurrent interactive sessions that takes an appreciable amount of time--a minute or two--and see if the time is overlapped or serialised. I have two Rgui sessions running now, but I don;t know enough about R to come up with something that doesn't complete instantaneously :(

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
RIP PCW It is as I've been saying!(Audio until 20090817)

In reply to Re^7: Using threads to run multiple external processes at the same time by BrowserUk
in thread Using threads to run multiple external processes at the same time by Anonymous Monk

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