Day 100

Day 100: PMI. Interesting observation #2

In this example I will demonstrate how changing numpy printoptions threshold affects the communication speed between Serial and Parallel. Honestly, I have no idea what printoptions threshold has to do with MPI or PMI communication speed and I am really tempted to investigate this issue further, but sadly don't have time for this at the moment. Anyway, output first (using mpirun with 2 nodes), then source code:

numpy_printoptions threshold set to 0
sending 200x200 numpy matrix with random elements
Sending x 10 times took 1.40654301643
numpy_printoptions threshold set to 201*201 (greater than the size of communicated matrix)
sending 200x200 numpy matrix with random elements
Sending x 10 times took 12.252920866

The numbers speak for themselves. The source code:

if __name__ != 'pmi':
    ##################################################
    ## Serial code
    ##################################################
    import pmi
    from time import time
    from numpy.random import beta
    from numpy import array, set_printoptions
    
    
    pmi.setup()
    
    pmi.execfile_(__file__)
    
    
    x = beta(a=1,b=1000,size=(200,200))

    # create a frontend class
    class Hello(object):
        def __init__(self, name):
            self.pmiobj = pmi.create('HelloLocal', name)
        def __call__(self):
            return pmi.invoke(self.pmiobj, '__call__')
        def time_send(self):
            t0 = time()
            for i in range(0,10):
                pmi.invoke(self.pmiobj,'recv',x)
            print "Sending x 10 times took",(time() - t0)
        def time_recv(self):
            t0 = time()
            for i in range(0,10):
                pmi.invoke(self.pmiobj,'send')
            print "Receiving x 10 times took",(time() - t0)

    # use the class
    hello = Hello('Konstantin')
    
    print "numpy_printoptions threshold set to 0"
    set_printoptions(threshold=0)
    print "sending 200x200 numpy matrix with random elements"
    hello.time_send()
    set_printoptions(threshold=201*201)
    print "numpy_printoptions threshold set to 201*201 (greater than the size of communicated matrix)"
    print "sending 200x200 numpy matrix with random elements"
    hello.time_send()
    
else:
    ##################################################
    ## Parallel code
    ##################################################
    from mpi4py import MPI
    from numpy.random import beta
    
    y = beta(a=1,b=1000,size=(100,100))

    class HelloLocal(object):
        def __init__(self, name):
            self.name = name
        def __call__(self):
            return 'Hello %s, this is MPI task %d!' % (self.name, MPI.COMM_WORLD.rank)
        def recv(self,x):
            "do nothing"
            
        def send(self):
            return y