Sympy multiprocessing

[Paul Royik]

I'm using sympy in my web-based project.

Specifically, I need to calculate integral.

However, I need to limit time and interrupt function.

Code, that I use.

import multiprocessing

class RunableProcessing(multiprocessing.Process):

    def __init__(self, func, *args, **kwargs):

        self.queue = multiprocessing.Queue(maxsize=1)

        args = (func,) + args

        multiprocessing.Process.__init__(self, target=self.run_func, args=args, kwargs=kwargs)

    def run_func(self, func, *args, **kwargs):

        try:

            result = func(*args, **kwargs)

            self.queue.put((True, result))

        except Exception as e:

            self.queue.put((False, e))

    def done(self):

        return self.queue.full()

    def result(self):

        return self.queue.get()

def timeout(seconds, func, *args, **kwargs):

    proc = RunableProcessing(func, *args, **kwargs)

    proc.start()

    proc.join(seconds)

    if proc.is_alive():

        proc.terminate()

        raise TimeoutException

    success, result = proc.result()

    if success:

        return result

    else:

        raise result

And here is simple part for integration

def wrapper(f,var):

    #do stuff

def int_wrapper(f, var):

   return f.integrate(var)

try:

    sol = timeout(10, wrapper, f, var)

except TimeoutException:

   print('timeout')

   try:

      sol = timeout(10, int_wrapper, f, var)

   except Exception:

      pass

However, there is weird thing.

I use django and when I access page for example with function x, it correctly outputs x^2/2, but when I access same page withour reloading server and wrapper raises timeout, for example, on f=sin(x)**120, integrate incorrrectly outputs x sin(x)**120.

I guess x under sine and integration x are different due to multiprocessing. Can somebody clarify situation? Maybe, there is problem with globals?

[Aaron Meurer]

I'd have to debug to see what is happening, but it's not too
surprising if there are issues with SymPy and multiprocessing because
SymPy has several issues with pickle
(https://github.com/sympy/sympy/search?q=pickle&ref=cmdform&state=open&type=Issues).

Aaron Meurer

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[Francesco Bonazzi]

On Friday, February 20, 2015 at 4:21:34 AM UTC+1, Aaron Meurer wrote:

because SymPy has several issues with pickle
(https://github.com/sympy/sympy/search?q=pickle&ref=cmdform&state=open&type=Issues).

What about creating a SymPy standardized type builder? That is, instead of defining custom classes in SymPy, one would use such a builder. Besides the pickle issues, it may address the var.func(*var.args) issue, and maybe provide some possible future integration with numba, when/if numba will provide C struct-like types.