python分布式计算框架PP(Parallel Python)集群模式试用

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分类专栏：软件语言与编程文章标签： python 分布式计算框架 parallel 集群

于 2016-08-28 19:56:08 首次发布

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本文介绍使用Parallel Python (PP) 库进行分布式计算的实践过程。通过两台不同配置的物理机搭建集群，测试了分布式计算的加速效果。结果显示，加速比达到5.1，有效利用了集群中的多个CPU资源。

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【标题】

python分布式计算框架PP(Parallel Python)集群模式试用

【背景】

Parallel Python库（简称PP）

网上的教程都是单机多进程测试，决定试试集群分布式计算效果

【结论】

用了两台物理机，一个4核，一个2核，集群分布式计算

可以看到最终加速比为5.1，计算方法是（60+27）/17=5.1。相当于5.1个CPU核心，比较充分地利用了多个计算机的多个CPU

【操作过程】

配置教程如下：

Parallel Python Documentation

计算子节点上，需要安装python，并安装pp库，

pip install pp 即可安装pp库

安装完成后，会有一个 ppserver.py在 scripts目录中

python ppserver.py -p 35000 -i 192.168.1.104 -s "123456"

该命令让计算子结点启动一个35000端口监听，mi ma是123456，自己的IP是192.168.1.104

主结点中创建ppserver实例时，需要指定ip列表，和secret，与之配合。

主结点运行任务时，可以动态负载均衡方式，发送任务给子结点

试用了官方提供的第一个demo，

Parallel Python Examples

并将测试数据改大一些，用了两台物理机，一个4核，一个2核，集群分布式计算

可以看到最终加速比为5.1，计算方法是（60+27）/17=5.1。相当于5.1个CPU核心，比较充分地利用了多个计算机的多个CPU

#!/usr/bin/python
# File: sum_primes.py
# Author: VItalii Vanovschi
# Desc: This program demonstrates parallel computations with pp module
# It calculates the sum of prime numbers below a given integer in parallel
# Parallel Python Software: http://www.parallelpython.com

import math, sys, time, datetime
import pp

def isprime(n):
    """Returns True if n is prime and False otherwise"""
    if not isinstance(n, int):
        raise TypeError("argument passed to is_prime is not of 'int' type")
    if n < 2:
        return False
    if n == 2:
        return True
    max = int(math.ceil(math.sqrt(n)))
    i = 2
    while i <= max:
        if n % i == 0:
            return False
        i += 1
    return True

def sum_primes(n):
    """Calculates sum of all primes below given integer n"""
    return sum([x for x in xrange(2,n) if isprime(x)])

print """Usage: python sum_primes.py [ncpus]
    [ncpus] - the number of workers to run in parallel, 
    if omitted it will be set to the number of processors in the system
"""

# tuple of all parallel python servers to connect with
#ppservers = ()
ppservers = ("192.168.1.104:35000",)
#ppservers=("*",)

if len(sys.argv) > 1:
    ncpus = int(sys.argv[1])
    # Creates jobserver with ncpus workers
    job_server = pp.Server(ncpus, ppservers=ppservers, secret="123456")
else:
    # Creates jobserver with automatically detected number of workers
    job_server = pp.Server(ppservers=ppservers, secret="123456")

print "Starting pp with", job_server.get_ncpus(), "workers"

# Submit a job of calulating sum_primes(100) for execution. 
# sum_primes - the function
# (100,) - tuple with arguments for sum_primes
# (isprime,) - tuple with functions on which function sum_primes depends
# ("math",) - tuple with module names which must be imported before sum_primes execution
# Execution starts as soon as one of the workers will become available
job1 = job_server.submit(sum_primes, (100,), (isprime,), ("math",))

# Retrieves the result calculated by job1
# The value of job1() is the same as sum_primes(100)
# If the job has not been finished yet, execution will wait here until result is available
result = job1()

print "Sum of primes below 100 is", result

start_time = time.time()

# The following submits 8 jobs and then retrieves the results
inputs = (500000, 500100, 500200, 500300, 500400, 500500, 500600, 500700, 500000, 500100, 500200, 500300, 500400, 500500, 500600, 500700)
#inputs = (1000000, 1000100, 1000200, 1000300, 1000400, 1000500, 1000600, 1000700)
jobs = [(input, job_server.submit(sum_primes,(input,), (isprime,), ("math",))) for input in inputs]
for input, job in jobs:
    print datetime.datetime.now()
    print "Sum of primes below", input, "is", job()

print "Time elapsed: ", time.time() - start_time, "s"
job_server.print_stats()

运行结果：

c:\Python27\python.exe test_pp_official.py

Usage: python sum_primes.py [ncpus]

[ncpus] - the number of workers to run in parallel,

if omitted it will be set to the number of processors in the system

Starting pp with 4 workers

Sum of primes below 100 is 1060

2016-08-28 19:07:26.579000

Sum of primes below 500000 is 9914236195

2016-08-28 19:07:33.032000

Sum of primes below 500100 is 9917236483

2016-08-28 19:07:33.035000

Sum of primes below 500200 is 9922237979

2016-08-28 19:07:33.296000

Sum of primes below 500300 is 9926740220

2016-08-28 19:07:33.552000

Sum of primes below 500400 is 9930743046

2016-08-28 19:07:33.821000

Sum of primes below 500500 is 9934746636

2016-08-28 19:07:34.061000

Sum of primes below 500600 is 9938250425

2016-08-28 19:07:37.199000

Sum of primes below 500700 is 9941254397

2016-08-28 19:07:37.202000

Sum of primes below 500000 is 9914236195

2016-08-28 19:07:41.640000

Sum of primes below 500100 is 9917236483

2016-08-28 19:07:41.742000

Sum of primes below 500200 is 9922237979

2016-08-28 19:07:41.746000

Sum of primes below 500300 is 9926740220

2016-08-28 19:07:41.749000

Sum of primes below 500400 is 9930743046

2016-08-28 19:07:41.752000

Sum of primes below 500500 is 9934746636

2016-08-28 19:07:41.756000

Sum of primes below 500600 is 9938250425

2016-08-28 19:07:43.846000

Sum of primes below 500700 is 9941254397

Time elapsed: 17.2770001888 s

Job execution statistics:

job count | % of all jobs | job time sum | time per job | job server

6 | 35.29 | 27.4460 | 4.574333 | 192.168.1.104:35000

11 | 64.71 | 60.2950 | 5.481364 | local

Time elapsed since server creation 17.2849998474

0 active tasks, 4 cores