multicore processing

test_multicore.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import time
import os
import multiprocessing
import numpy as np



def threshold(plane, t=0.5):
    """ threshold all array values """
    bw = np.zeros(plane.shape, dtype = np.uint8)

    for idx,x in np.ndenumerate(plane):
        bw[idx] = 1*(x>t)
        
    return bw

def doWork(plane,idx,q):
    """ function for multithring """
    bw = threshold(plane)
    q.put((bw,idx))


if __name__ == "__main__":
    
    
    N = 1000
    nrPlanes = 4
    
    fullMat = np.random.rand(N,N,nrPlanes)
    print('Starting single thread')
    # sequential --------------------
    tStart = time.time()
    bw = np.zeros(fullMat.shape)
    
    for i in range(nrPlanes):
        plane = fullMat[:,:,i]
        bw[:,:,i] = threshold(plane)
    
    tSingle = time.time() - tStart
    print('Single thread done in %.3f seconds' % tSingle)
    
    # parallel -----------------------------------
    tStart = time.time()
    
    bw2 = np.zeros(fullMat.shape)
    q = multiprocessing.Queue()
    processes = []
    # create subprocesses
    for iPlane in range(nrPlanes):
        print('Starting processing plane ', iPlane)
        p = multiprocessing.Process(target=doWork, args=(fullMat[:,:,iPlane],iPlane,q))
        p.start()
        processes.append(p)
        
    print('Getting results..')
    for idx in range(nrPlanes):
        res = q.get(True)
        iPlane = res[1]
        print('Processed plane ',iPlane)
        bw2[:,:,iPlane] = res[0]

    for p in processes:
        p.join()

    tMulti = time.time() - tStart
    print('Multiple thread done in %.3f seconds' % tMulti)
    print('Speedup: %.2f x' % (tSingle/tMulti))
    
    assert (bw==bw2).all(), 'Results not equal!'