[C++-sig] Why can't kill process by Ctrl-c in a boost.python module with an endless loop
simon zhang
hapopen at gmail.com
Mon Dec 24 08:27:57 CET 2012
Because string's memory allocated is different in python and c++.General
method should not suited.
I have reviewed the project.Maybe you're right, it is premature to optimize
the program.At least for now, it should not be a problem.
The program will have a c + + interface and a python interface, so I'm
doing some complicated.
I will use a simple method.The data will be copied.
In the future, I will be write a wrapped class. When the c++ interface,
it store the data by std :: string.When the python interface,it store the
data by the Python str object. And perhaps this is a good way.
What do you think?
2012/12/24 Jaedyn K. Draper <jaedyn.cppsig at jaedyn.co>
> Yeah, I saw your other question about it. There's nothing in boost that I
> know of to achieve that. The only thing I'd know to suggest is what others
> have already suggested - encapsulate it in another class and pass that in.
> But it wouldn't be converted to a python string that way.
>
> My question is whether or not you may be trying to optimize prematurely.
> If your performance needs are strict enough that you need to pass your
> string as a pointer, might it be better to write your application in C++
> entirely, or prototype in python and then convert to C++?
>
> You might try passing it as a reference instead of a pointer. I don't know
> if that'll work or not. But, try having a regular std::string instead of a
> std::string* and send it using ref(str) (the same way that I suggested you
> send things using ptr() in your earlier question). Again, I don't know if
> it'll work, but it might be worth a try.
>
> If it's a return value, returning a ref() would cause a local variable to
> go out of scope. You could try passing the desired string as a reference
> parameter, rather than trying to return it. Again, I'm not sure if this
> will work or not, as I've never tried it.
>
> If neither of those work, I'd have to play around with it some to see if I
> could come up with anything else.
>
>
> On 12/23/2012 11:41 PM, simon zhang wrote:
>
> Jaedyn.
>
> I would like to discuss another issue, what is a good way to avoid deep
> copy.There may be a few big data.From c++ to python and from python to
> c++.Similar from c + + return std::string* to python and python pass the
> std::string* parameter to c + + function.Maybe it should be similar to
> smart pointers.Do you have any good suggestions in there?
>
>
> 2012/12/23 Jaedyn K. Draper <jaedyn.cppsig at jaedyn.co>
>
>> I was at least half right, then. Python was eating the signals. :)
>>
>> As an alternative, to prevent yourself from having to do this in every
>> loop in your code, you might try this on the python side:
>>
>> import signal
>> signal.signal(signal.SIGINT, signal.SIG_DFL)
>>
>> That'll stop Python from catching SIGINT globally and will always send
>> the SIGINT down to the C++ and terminate.
>>
>> Of course, that may or may not be an option depending on your specific
>> needs.
>>
>>
>> On 12/23/2012 3:02 AM, simon zhang wrote:
>>
>> This is the answer from the stackoverflow.
>>
>> while (true) { //endless loop
>> ++it;
>> std::cout<< it <<std::endl;
>> sleep(3);
>> if(PyErr_CheckSignals() == -1) {
>> exit(1);
>> }
>> }
>>
>>
>> 2012/12/23 Jaedyn K. Draper <jaedyn.cppsig at jaedyn.co>
>>
>>> Oh, my mistake. Not sure then, I've only embedded, never extended.
>>> Maybe someone else can help. :(
>>>
>>>
>>> On 12/23/2012 1:59 AM, simon zhang wrote:
>>>
>>> But I don't call Py_Initialize().I call C++ code in Python.Don't embed
>>> the Python to C++...
>>>
>>> 2012/12/23 Jaedyn K. Draper <jaedyn.cppsig at jaedyn.co>
>>>
>>>> Instead of Py_Initialize() (wherever it is you call it), try calling
>>>> Py_InitializeEx(0). Py_Initialize() (or Py_InitializeEx(1)) binds signal
>>>> handlers (including SIGINT) to send python exceptions instead of killing
>>>> the process. This may be what's hitting you.
>>>>
>>>>
>>>> On 12/23/2012 1:44 AM, simon zhang wrote:
>>>>
>>>> I have make a boost.python module with an endless loop.But I can't
>>>> kill the process by ctrl-c.The following is an example.
>>>>
>>>> C++
>>>>
>>>> #include <boost/python.hpp>#include <boost/python.
>>>> module.hpp>#include <boost/python.
>>>> def.hpp>#include <iostream>
>>>> usring namespace boost::python;
>>>> void foo() {
>>>> int it=0;
>>>> while (true) { //endless loop
>>>> ++it;
>>>> std::cout<< it <<std::endl;
>>>> sleep(3);
>>>> }}
>>>>
>>>> BOOST_PYTHON_MODULE(ctopy){
>>>> def("foo",foo);}
>>>>
>>>> python:
>>>>
>>>> import ctopy
>>>> ctopy.foo()
>>>>
>>>> result:
>>>>
>>>> 1234.....................
>>>>
>>>> I can't kill the foreground process by Ctrl-c.why the module don't
>>>> accept signal "SIGINT" that was sent by Ctrl-c.How to make it work.
>>>>
>>>>
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