Python randomly drops to 0% CPU usage, causing the code to “hang up”, when handling large numpy arrays?

Question

I have been running some code, a part of which loads in a large 1D numpy array from a binary file, and then alters the array using the numpy.where() method.

Here is

Answer 1

The drops in CPU usage were unrelated to python or numpy, but were indeed a result of reading from a shared disk, and network I/O was the real culprit. For such large arrays, reading into memory can be a major bottleneck.