Re: how avoid delay while returning from C-python api?
Yes, Cython looks easier but the problem its a very old code ( 6 or 7 years ). Almost entire code base uses plain python-c api. Thanks for the example, will use Cython or Ctypes way for side-projects! Cheers, Lakshmipathi.G FOSS Programmer. www.giis.co.in/readme.html -- https://mail.python.org/mailman/listinfo/python-list
Re: how avoid delay while returning from C-python api?
On 5/28/14 6:22 AM, Lakshmipathi.G wrote:
Hi -
I have C-Python api like below. It works fine, but the problem is
while invoking this method
from python script say
#cat script.py
snip
offset=0
size=4
write_object(offset,size)
/snip
This calls write_this_c() C api and returns quickly to next printf statement.
But the return call (Py_RETURN_NONE) takes something like 4-6 seconds.
-
static
PyMethodDef xyz_methods[] = {
{write_object, write_object, METH_VARARGS,write some stuff },
{NULL, NULL, 0, NULL}
};
static PyObject *
write_object(PyObject *self, PyObject *args)
{
int offset, size;
if (!PyArg_ParseTuple(args,ii, offset, size))
Py_RETURN_NONE;
printf(before call);
write_this_c(offset, size);
printf(after call);
Py_RETURN_NONE; ##delay happens here
}
How to avoid this delay time? Thanks for any help/pointers!
It can't be as simple as the Py_RETURN_NONE taking 4-6 seconds: hundreds
of built-in functions in Python are coded exactly this way, and they
don't have a delay on return. Something else is going on.
How did you determine that it was the return that was taking the time?
Cheers,
Lakshmipathi.G
FOSS Programmer.
www.giis.co.in
--
Ned Batchelder, http://nedbatchelder.com
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Re: how avoid delay while returning from C-python api?
The statement after call printed to stdout and the script waits there for few seconds. So I was assuming something delaying the return value. Just found out there is core-dump segmentation fault (core dumped) python ..Probably fixing core dump should resolve the issue. Thanks! Cheers, Lakshmipathi.G FOSS Programmer. www.giis.co.in -- https://mail.python.org/mailman/listinfo/python-list
Re: how avoid delay while returning from C-python api?
Lakshmipathi.G, 28.05.2014 12:22:
I have C-Python api like below. It works fine, but the problem is
while invoking this method
from python script say
#cat script.py
snip
offset=0
size=4
write_object(offset,size)
/snip
This calls write_this_c() C api and returns quickly to next printf statement.
But the return call (Py_RETURN_NONE) takes something like 4-6 seconds.
-
static
PyMethodDef xyz_methods[] = {
{write_object, write_object, METH_VARARGS,write some stuff },
{NULL, NULL, 0, NULL}
};
static PyObject *
write_object(PyObject *self, PyObject *args)
{
int offset, size;
if (!PyArg_ParseTuple(args,ii, offset, size))
Py_RETURN_NONE;
printf(before call);
write_this_c(offset, size);
printf(after call);
Py_RETURN_NONE; ##delay happens here
}
How to avoid this delay time? Thanks for any help/pointers!
You already found the problem yourself, so let me just give you a general
advice that you can avoid a lot of the hassle of writing code like the
above and struggling to get it right by writing it in Cython instead of
plain C. Here's a complete example of the above code in Cython, including
the module setup code etc., but without the bugs:
# external declarations:
cdef extern from someheader.h:
void write_this_c(int offset, int size)
# your module function:
def write_object(int offset, int size):
write some stuff
print(before call)
write_this_c(offset, size)
print(after call)
That's it.
Stefan
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