1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/examples/simple_background_queue.py Mon Jun 02 22:44:33 2008 +0000
1.3 @@ -0,0 +1,106 @@
1.4 +#!/usr/bin/env python
1.5 +
1.6 +"""
1.7 +A simple example of parallel computation using a queue, background callables and
1.8 +persistent communications.
1.9 +"""
1.10 +
1.11 +import pprocess
1.12 +import time
1.13 +#import random
1.14 +import sys
1.15 +
1.16 +# Array size and a limit on the number of processes.
1.17 +
1.18 +N = 10
1.19 +limit = 10
1.20 +delay = 1
1.21 +
1.22 +# Work function and monitoring class.
1.23 +
1.24 +def calculate(i, j):
1.25 +
1.26 + """
1.27 + A supposedly time-consuming calculation on 'i' and 'j'.
1.28 + """
1.29 +
1.30 + #time.sleep(delay * random.random())
1.31 + time.sleep(delay)
1.32 + return (i, j, i * N + j)
1.33 +
1.34 +# Main computation.
1.35 +
1.36 +def task():
1.37 +
1.38 + # Initialise the communications queue with a limit on the number of
1.39 + # channels/processes.
1.40 +
1.41 + queue = pprocess.Queue(limit=limit)
1.42 +
1.43 + # Initialise an array.
1.44 +
1.45 + results = [0] * N * N
1.46 +
1.47 + # Wrap the calculate function and manage it.
1.48 +
1.49 + calc = queue.manage(pprocess.MakeParallel(calculate))
1.50 +
1.51 + # Perform the work.
1.52 +
1.53 + print "Calculating..."
1.54 + for i in range(0, N):
1.55 + for j in range(0, N):
1.56 + calc(i, j)
1.57 +
1.58 + # Store the results as they arrive.
1.59 +
1.60 + print "Finishing..."
1.61 + for i, j, result in queue:
1.62 + results[i*N+j] = result
1.63 +
1.64 + return results
1.65 +
1.66 +# Main program.
1.67 +
1.68 +if __name__ == "__main__":
1.69 +
1.70 + t = time.time()
1.71 +
1.72 + if "--reconnect" not in sys.argv:
1.73 +
1.74 + # Wrap the computation and manage it.
1.75 +
1.76 + ptask = pprocess.BackgroundCallable("task.socket", pprocess.MakeParallel(task))
1.77 +
1.78 + # Perform the work.
1.79 +
1.80 + ptask()
1.81 +
1.82 + # Discard the callable.
1.83 +
1.84 + del ptask
1.85 + print "Discarded the callable."
1.86 +
1.87 + if "--start" not in sys.argv:
1.88 +
1.89 + # Open a queue and reconnect to the task.
1.90 +
1.91 + print "Opening a queue."
1.92 + queue = pprocess.BackgroundQueue("task.socket")
1.93 +
1.94 + # Wait for the results.
1.95 +
1.96 + print "Waiting for persistent results"
1.97 + for results in queue:
1.98 + pass # should only be one element
1.99 +
1.100 + # Show the results.
1.101 +
1.102 + for i in range(0, N):
1.103 + for result in results[i*N:i*N+N]:
1.104 + print result,
1.105 + print
1.106 +
1.107 + print "Time taken:", time.time() - t
1.108 +
1.109 +# vim: tabstop=4 expandtab shiftwidth=4