# cypress/FileTransfer/Example: sum_primes.py

File sum_primes.py, 2.5 KB (added by cmaggio, 7 years ago)
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1# File: sum_primes.py
2# Author: VItalii Vanovschi
3# Desc: This program demonstrates parallel computations with pp module
4# It calculates the sum of prime numbers below a given integer in parallel
5# Parallel Python Software: http://www.parallelpython.com
6
7import math, sys, time
8import pp
9
10def isprime(n):
11    """Returns True if n is prime and False otherwise"""
12    if not isinstance(n, int):
13        raise TypeError("argument passed to is_prime is not of 'int' type")
14    if n < 2:
15        return False
16    if n == 2:
17        return True
18    max = int(math.ceil(math.sqrt(n)))
19    i = 2
20    while i <= max:
21        if n % i == 0:
22            return False
23        i += 1
24    return True
25
26def sum_primes(n):
27    """Calculates sum of all primes below given integer n"""
28    return sum([x for x in xrange(2,n) if isprime(x)])
29
30print """Usage: python sum_primes.py [ncpus]
31    [ncpus] - the number of workers to run in parallel,
32    if omitted it will be set to the number of processors in the system
33"""
34
35# tuple of all parallel python servers to connect with
36ppservers = ()
37#ppservers = ("10.0.0.1",)
38
39if len(sys.argv) > 1:
40    ncpus = int(sys.argv)
41    # Creates jobserver with ncpus workers
42    job_server = pp.Server(ncpus, ppservers=ppservers)
43else:
44    # Creates jobserver with automatically detected number of workers
45    job_server = pp.Server(ppservers=ppservers)
46
47print "Starting pp with", job_server.get_ncpus(), "workers"
48
49# Submit a job of calulating sum_primes(100) for execution.
50# sum_primes - the function
51# (100,) - tuple with arguments for sum_primes
52# (isprime,) - tuple with functions on which function sum_primes depends
53# ("math",) - tuple with module names which must be imported before sum_primes execution
54# Execution starts as soon as one of the workers will become available
55job1 = job_server.submit(sum_primes, (100,), (isprime,), ("math",))
56
57# Retrieves the result calculated by job1
58# The value of job1() is the same as sum_primes(100)
59# If the job has not been finished yet, execution will wait here until result is available
60result = job1()
61
62print "Sum of primes below 100 is", result
63
64start_time = time.time()
65
66# The following submits 8 jobs and then retrieves the results
67inputs = (100000, 100100, 100200, 100300, 100400, 100500, 100600, 100700)
68jobs = [(input, job_server.submit(sum_primes,(input,), (isprime,), ("math",))) for input in inputs]
69for input, job in jobs:
70    print "Sum of primes below", input, "is", job()
71
72print "Time elapsed: ", time.time() - start_time, "s"
73job_server.print_stats()
74
75# Parallel Python Software: http://www.parallelpython.com