From peter.juhasz83 at gmail.com  Mon Sep  7 17:36:38 2009
From: peter.juhasz83 at gmail.com (Peter Juhasz)
Date: Mon, 7 Sep 2009 17:36:38 +0200
Subject: [Rd] Running two R instances at the same time
In-Reply-To: <20090907144728.GA85931@piskorski.com>
References: <b2050ab90909051131i15b413bci18300426406cbcea@mail.gmail.com>
	<20090907144728.GA85931@piskorski.com>
Message-ID: <b2050ab90909070836w5fc0bbc5t643dcef4b06e7dba@mail.gmail.com>

On Mon, Sep 7, 2009 at 4:47 PM, Andrew Piskorski<atp at piskorski.com> wrote:
> On Sat, Sep 05, 2009 at 08:31:18PM +0200, Peter Juhasz wrote:
>
>> I don't understand how is this possible. Maybe there is an issue of
>> thread-safety with the R backend, meaning that the two R *interpreter*
>> instances are talking to the same backend that's capable of processing
>> only one thing at a time?
>
> No. ?Particularly since there is no R "backend" involved at all, not
> if you're starting up the standard R from Ubuntu 9.04 (rather than
> Rserve or something else unusual). ?People run multiple R processes
> concurrently on the same (multi-core) machine all the time, works
> fine.
>
>> Please see http://www.perlmonks.org/?node_id=792460 for an extended
>> discussion of the problem, and especially
>> http://www.perlmonks.org/?node_id=793506 for excerpts of output and
>> actual code.
>
> The most likely explanation seems to be that you have a bug in your
> Perl code. ?Have you tried using your Perl framework to fork something
> OTHER than R? ?Have you tried manually starting up two R processes and
> running your R code that way? ?And, what is the actual R code you're
> running? ?You don't seem to have shown it anywhere.
>
> --
> Andrew Piskorski <atp at piskorski.com>
> http://www.piskorski.com/
>

Actually, I have ran some tests that clarified the issue somewhat.

- It is always possible that my Perl code is buggy but that doesn't
seem to play a role in this case.
- I tried to use my Perl system to start two non-R processes - it
worked as expected, they ran concurrently without ill effects.

But please see http://www.perlmonks.org/index.pl?node_id=793907 ,
where I posted my R code in its simplest form along with an example
run which exhibits the symptoms I originally wrote about.

>From that test I conclude that it is not my Perl code nor R itself
that is wrong here, but the specific package I use. That package -
NADA, from which I use the 'cenros' command - seems to be the culprit.

Please forgive my complete lack of experience when it comes to R, this
made me assume things that didn't make sense.

P?ter Juh?sz



[Rd] Running two R instances at the same time
Peter Juhasz