Bugs item #2062627, was opened at 2008-08-20 16:01
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Category: Source
Group: rpy
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: R cannot initialize more than once in process
Initial Comment:
Hello,
I am currently working with a software package (ArcGIS) that runs Python In
Process. There has been a call from our users to be able to integrate R
functionality. Our Out of Proc version allows us to call rpy over and over
again because it is essentially re-initializing the R() instance on each run.
But when we switch it over to the In Proc version we get the following error
message:
Traceback (most recent call last):
File "<string>", line 29, in <module>
File "<string>", line 8, in testPoly2Line
File "C:\Python25\lib\site-packages\rpy.py", line 346, in <module> r = R()
File "C:\Python25\lib\site-packages\rpy.py", line 286, in __init__
_rpy.r_init(HAS_NUMERIC);
RuntimeError: Only one R object may be instantiated per session
The problem can be explained by the following set of issues: 1) We embed Python
in our application for use as a scripting engine, 2) Each time a Python script
is run in the application, it is from a new Python session (i.e. a brand new
set of locals and globals) but in the same process, 3) When importing the
Python R libraries, it binds the RPy .DLL into process, 4) In Python Rs
startup, there is a static integer in _rpy.r_init used as a flag that
determines if R has already been loaded. The rest of the function initializes
numeric if sent the flag to do so, and throws a RuntimeError if R was
initialized before. Since the library is still resident in memory even after
the Python session goes away, this stays set to 1. Looking at the C
implementation of the r_init function, this seems unnecessary and there have
been no ill effects from patching the Python to ignore the error. After a
cursory read over the Python, this appears to be a piece of legacy that isnt
necessary anymore
as it does not affect anything else.
We have a hack that allows us to run it In Proc and we wanted to know if it is
appropriate: (On Line ~ 286 of rpy.py)
try:
_rpy.r_init(HAS_NUMERIC)
except RuntimeError, e:
pass
_rpy.set_mode(NO_DEFAULT)
So in our case, RPythons refusal to instantiate another instance of the R()
object by throwing a RuntimeError is considered a bug, because the binary
library is already initialized and resident in memory, its related Python
locals just went away and need to be allowed to reset. Ignoring the error is
idea, but warning instead of throwing is, at the very least, preferable.
Ideally the code in C would more resemble this:
static PyObject *
r_init(PyObject *self, PyObject *args)
{
static int first=1;
int i;
if (!PyArg_ParseTuple(args, "i:r_init", &i))
return NULL;
use_numeric = i;
if(first==1)
{
#ifdef WITH_NUMERIC
if(use_numeric)
init_numeric();
#endif
first=0;
}
Py_INCREF(Py_None);
return Py_None;
}
Thanks so much ahead of time. Best wishes,
MJ
Mark Janikas
Product Engineer
ESRI, Geoprocessing
380 New York St.
Redlands, CA 92373
909-793-2853 (2563)
[EMAIL PROTECTED]
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