Hello Urbanek,
Simon Urbanek wrote:
Keith,
On Nov 19, 2010, at 7:40 PM, Keith wrote:
Dear R users,
I have a small project written in Java and need some statical tools. Therefore,
I used JRI (in rJava package) as an interface between R and Java to write some
wrappers for my work. However, I received error message from R while I have
more than one java method which wraps R:
Error in .Call("R_isMethodsDispatchOn", onOff, PACKAGE = "base") :
Incorrect number of arguments (2), expecting 1 for R_isMethodsDispatchOn
The Java pseudo code would be like:
public class Test{
public static void main(String[] args){
...
objA.do;
objB.do;
...
}
}
Each do method actually calls R to do the job. I already know R is
single-treaded so I implemented end method in Rengine class to shutdown R in
each method.
You cannot shutdown R short of closing the process and thus JVM, so that is not
an option. In fact NOT using end will likely solve your problem - simply used
one, shared instance of the REngine.
I thought this won't cause multi-thread problems in this case because I
terminate/destroy each R thread before I call another one. But, it seems that
it's still considered as 2 threads. Did I miss something? or probably, I have
to set-up JRI server for my project? or other recommendations for my purpose?
Simply use one instance of REngine continuously - that's the only approach
possible with JRI (note that the R access is synchronized so you can use the
instance from different threads). If you need multiple instances, you can use
Rserve - it uses the same REngine API but allows you to have arbitrarily many
parallel instances.
BTW: please use stats-rosuda-devel mailing list of questions related to rJava,
JRI or Rserve. It's also worth scanning the archives as those issues have been
raised before.
Cheers,
Simon
R version: 2.11.1
rJava version: 0.8-4
OS: Arch Linux
Best,
Keith
Thanks for the quick reply. It clears my confusion of using JRI. Now I
knew the stats-rosuda-devel mailing list, and I'll raise the related
questions/problems there next time.
Cheers,
Keith
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