Charm4py (Charm++ for Python -formerly CharmPy-) is a distributed computing and
parallel programming framework for Python, for the productive development of fast,
parallel and scalable applications.
It is built on top of
Charm++_, a C++ adaptive runtime system that has seen
extensive use in the scientific and high-performance computing (HPC) communities
across many disciplines, and has been used to develop applications that run on a
wide range of devices: from small multi-core devices up to the largest supercomputers.
Please see the Documentation_ for more information.
The following computes Pi in parallel, using any number of machines and processors:
.. code-block:: python
from charm4py import charm, Chare, Group, Reducer, Future from math import pi import time class Worker(Chare): def work(self, n_steps, pi_future): h = 1.0 / n_steps s = 0.0 for i in range(self.thisIndex, n_steps, charm.numPes()): x = h * (i + 0.5) s += 4.0 / (1.0 + x**2) # perform a reduction among members of the group, sending the result to the future self.reduce(pi_future, s * h, Reducer.sum) def main(args): n_steps = 1000 if len(args) > 1: n_steps = int(args) mypi = Future() workers = Group(Worker) # create one instance of Worker on every processor t0 = time.time() workers.work(n_steps, mypi) # invoke 'work' method on every worker print('Approximated value of pi is:', mypi.get(), # 'get' blocks until result arrives 'Error is', abs(mypi.get() - pi), 'Elapsed time=', time.time() - t0) exit() charm.start(main)
This is a simple example and demonstrates only a few features of Charm4py. Some things to note from this example:
In this example, there is only one chare per processor, but multiple chares (of the same or different type) can exist on any given processor, which can bring flexibility and also performance benefits (like dynamic load balancing). Please refer to the documentation_ for more information.
We would like feedback from the community. If you have feature suggestions,
support questions or general comments, please visit our
or emails us at [email protected], or
Main author at [email protected]
.. _Charm++: https://github.com/UIUC-PPL/charm
.. _Documentation: https://charm4py.readthedocs.io
.. _forum: https://charm.discourse.group/c/charm4py