Usually a remote method invocation results in serialization of the arguments
into a message that is sent to a remote process.
For many situations, Charm4py relies on Python’s
Pickling is bypassed for certain data types that implement the buffer protocol (byte arrays, array.array and NumPy arrays) and is encouraged for best performance. For these, the data is directly copied from its memory buffer in Python into a message in the Charm C++ library for sending. The Performance Tips section explains how to take advantage of this.
Pickling can account for much of the overhead of the Charm4py runtime. Fastest
pickling is obtained with the C implementation of the
(only available in CPython).
A general guideline to achieve good pickle performance is to avoid passing custom types as
arguments to remote methods in the application’s critical path.
Examples of recommended types to use for best performance include: Python containers
(lists, dicts, set), basic datatypes (int, float, str, bytes) or combinations of the
above (e.g.: dict containing lists of ints). Custom objects are automatically
pickled but can significantly affect the performance of pickle and therefore their
use inside the critical path is not recommended.