On Tue, 27 Feb 2007, Ernest Turro wrote:
> Hi Ross,
>
> On 26 Feb 2007, at 22:34, Ross Boylan wrote:
>
>> On Mon, 2007-02-26 at 16:08 +0000, Ernest Turro wrote:
>>> Thanks for your comments Ross. A couple more comments/queries below:
>>>
>>> On 26 Feb 2007, at 06:43, Ross Boylan wrote:
>>>
>>>> [details snipped]
>>>>
>>>> The use of the R api can be confined to a wrapper function. But
>>>> I can
>>>> think of no reason that a change to the alternate approach I
>>>> outlined
>>>> would solve the apparent leaking you describe.
>>>>
>>>
>>> I'm not sure I see how a wrapper function using the R API would
>>> suffice. Example:
>> It doesn't sound as if it would suffice. I was responding to your
>> original remark that
>>
>>> Since this is a standalone C++ program too, I'd rather use the R API
>>> as little as possible... But I will look at your solution if I find
>>> it is really necessary.. Thanks
>>
>> I thought that was expressing a concern about using the alternate
>> approach I outlined because it would use the R API. If you need to
>> use
>> that API for other reasons, you're still stuck with it :)
>>>
>>> During heavy computation in the C++ function I need to allow
>>> interrupts from R. This means that R_CheckUserInterrupt needs to be
>>> called during the computation. Therefore, use of the R API can't be
>>> confined to just the wrapper function.
>>>
>>> In fact, I'm worried that some of the libraries I'm using are failing
>>> to release memory after interrupt and that that is the problem. I
>>> can't see what I could do about that... E.g.
>>>
>>> #include <valarray>
>>>
>>> valarray<double> foo; // I don't know 100% that the foo object hasn't
>>> allocated some memory. if the program is interrupted it wouldn't be
>>> released....
>> That's certainly possible, but you seem to be overlooking the
>> possibility that all the code is releasing memory appropriately,
>> but the
>> process's memory footprint isn't going down correspondingly. In my
>> experience that's fairly typical behavior.
>>
>
> OK, but does this still explain why the footprint keeps increasing
> indefinitely when i do run, interrupt, run, interrupt, run,
> interrupt......?
>
>
>> In that case, depending on your point of view, you either don't have a
>> problem or you have a hard problem. If you really want the memory
>> released back to the system, it's a hard problem. If you don't
>> care, as
>> long as you have no leaks, all's well.
>>
>>>
>>> I find it's very unfortunate that R_CheckUserInterrupt doesn't return
>>> a value. If it did (e.g. if it returned true if an interrupt has
>>> occurred), I could just branch off somewhere, clean up properly and
>>> return to R.
>>>
>>> Any ideas on how this could be achieved?
>> I can't tell from the info page what function gets called in R if
>> there
>> is an interrupt, but it sounds as you could do the following hack:
>> The R interrupt handler gets a function that calls a C function of
>> your
>> devising. The C function sets a flag meaning "interrupt requested".
>> Then in your main code, you periodically call R_CheckUserInterrupt.
>> When it returns you check the flag; if it's set, you cleanup and exit.
>> Ross
>>
>
> If this is feasible, it's by far the best solution.
>
> in error.c:
>
> void R_CheckUserInterrupt(void)
> {
> R_CheckStack();
> /* This is the point where GUI systems need to do enough event
> processing to determine whether there is a user interrupt event
> pending. Need to be careful not to do too much event
> processing though: if event handlers written in R are allowed
> to run at this point then we end up with concurrent R
> evaluations and that can cause problems until we have proper
> concurrency support. LT */
> #if ( defined(HAVE_AQUA) || defined(Win32) )
> R_ProcessEvents();
> #else
> if (R_interrupts_pending)
> onintr();
> #endif /* Win32 */
> }
>
> Leaving aside the HAVE_AQUA and Win32 cases, I would like to write a
> new function:
Unfortunately we can't leave those aside. If standard unix where
interrupts arrive as signals is all you care about then you can just
save, replace and restore the R SIGINT handler around your code with
one that sets a flag of your own. Things are not so simple on GUI
systems where detecting a user interrupt action requires event
processing, which might result in errors and non-local exits in
response to those.
There is an internal mechanism for registering C level on.exit
routines but this is not in a form that can be made public as it would
tie down implementation decisions too much. It is principle possible
to build something around R_ToplevelExec, but that is not at this
point part of the public API and so is subject to change. We might
consider providing a variant of R_CheckInterrupts that either just
checks or that executes cleanup code sometime after 2.5 is released.
Best,
luke
>
> int R_CheckInterruptsPending(void)
> {
> R_CheckStack();
> return R_interrupts_pending;
> }
>
> and then in my C++ code:
>
> if(R_checkInterruptsPending) {
> // clean up
> // ...
> R_CheckInterruptsPending();
> }
>
> R_CheckStack() is declared in R_ext/Utils.h but the variable
> R_interrupts_pending isn't, so how could I access it? In other words,
> how can I extend error.c .....
>
>
> Thanks,
>
> E
>
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>
--
Luke Tierney
Chair, Statistics and Actuarial Science
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: [EMAIL PROTECTED]
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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