Parallel Python Documentation

Module API
Quick start guide, SMP
Quick start guide, clusters
Quick start guide, clusters with auto-discovery
Advanced guide, clusters
Command line arguments, ppserver.py
Security and secret key
ppserver.py stats and PID file example
PP FAQ


pp 1.6 module API


class Server
Parallel Python SMP execution server class
Methods defined here:
__init__(self, ncpus='autodetect', ppservers=(), secret=None, restart=False, proto=2, socket_timeout=3600)
Creates Server instance
ncpus - the number of worker processes to start on the local
computer, if parameter is omitted it will be set to
the number of processors in the system
ppservers - list of active parallel python execution servers
to connect with
secret - passphrase for network connections, if omitted a default
passphrase will be used. It's highly recommended to use a
custom passphrase for all network connections.
restart - whether to restart worker process after each task completion
proto - protocol number for pickle module
socket_timeout - socket timeout in seconds which is also the maximum
time a remote job could be executed. Increase this value
if you have long running jobs or decrease if connectivity
to remote ppservers is often lost.

With ncpus = 1 all tasks are executed consequently
For the best performance either use the default "autodetect" value
or set ncpus to the total number of processors in the system
destroy(self)
Kills ppworkers and closes open files
get_active_nodes(self)
Returns active nodes as a dictionary
[keys - nodes, values - ncpus]
get_ncpus(self)
Returns the number of local worker processes (ppworkers)
get_stats(self)
Returns job execution statistics as a dictionary
print_stats(self)
Prints job execution statistics. Useful for benchmarking on
clusters
set_ncpus(self, ncpus='autodetect')
Sets the number of local worker processes (ppworkers)

ncpus - the number of worker processes, if parammeter is omitted
it will be set to the number of processors in the system
submit(self, func, args=(), depfuncs=(), modules=(), callback=None, callbackargs=(), group='default', globals=None)
Submits function to the execution queue

func - function to be executed
args - tuple with arguments of the 'func'
depfuncs - tuple with functions which might be called from 'func'
modules - tuple with module names to import
callback - callback function which will be called with argument
list equal to callbackargs+(result,)
as soon as calculation is done
callbackargs - additional arguments for callback function
group - job group, is used when wait(group) is called to wait for
jobs in a given group to finish
globals - dictionary from which all modules, functions and classes
will be imported, for instance: globals=globals()
wait(self, group=None)
Waits for all jobs in a given group to finish.
If group is omitted waits for all jobs to finish
default_port = 60000
default_secret = 'epo20pdosl;dksldkmm'


class Template
Template class
Methods defined here:
__init__(self, job_server, func, depfuncs=(), modules=(), callback=None, callbackargs=(), group='default', globals=None)
Creates Template instance

jobs_server - pp server for submitting jobs
func - function to be executed
depfuncs - tuple with functions which might be called from 'func'
modules - tuple with module names to import
callback - callback function which will be called with argument
list equal to callbackargs+(result,)
as soon as calculation is done
callbackargs - additional arguments for callback function
group - job group, is used when wait(group) is called to wait for
jobs in a given group to finish
globals - dictionary from which all modules, functions and classes
will be imported, for instance: globals=globals()
submit(self, *args)
Submits function with *arg arguments to the execution queue


Data
copyright = 'Copyright (c) 2005-2012 Vitalii Vanovschi. All rights reserved'
version = '1.6'


Quick start guide, SMP

1) Import pp module:

import pp

2) Start pp execution server with the number of workers set to the number of processors in the system

job_server = pp.Server()

3) Submit all the tasks for parallel execution:

f1 = job_server.submit(func1, args1, depfuncs1, modules1)

f2 = job_server.submit(func1, args2, depfuncs1, modules1)

f3 = job_server.submit(func2, args3, depfuncs2, modules2)

...etc...

4) Retrieve the results as needed:

r1 = f1()

r2 = f2()

r3 = f3()

...etc...

To find out how to achieve efficient parallelization with pp please take a look at examples


Quick start guide, clusters

On the nodes

1) Start parallel python execution server on all your remote computational nodes:

node-1> ./ppserver.py

node-2> ./ppserver.py

node-3> ./ppserver.py

On the client

2) Import pp module:

import pp

3) Create a list of all the nodes in your cluster (computers where you've run ppserver.py)

ppservers=("node-1", "node-2", "node-3")

4) Start pp execution server with the number of workers set to the number of processors in the system and list of ppservers to connect with :

job_server = pp.Server(ppservers=ppservers)

5) Submit all the tasks for parallel execution:

f1 = job_server.submit(func1, args1, depfuncs1, modules1)

f2 = job_server.submit(func1, args2, depfuncs1, modules1)

f3 = job_server.submit(func2, args3, depfuncs2, modules2)

...etc...

6) Retrieve the results as needed:

r1 = f1()

r2 = f2()

r3 = f3()

...etc...

To find out how to achieve efficient parallelization with pp please take a look at examples


Quick start guide, clusters with autodiscovery

On the nodes

1) Start parallel python execution server on all your remote computational nodes:

node-1> ./ppserver.py -a

node-2> ./ppserver.py -a

node-3> ./ppserver.py -a

On the client

2) Import pp module:

import pp

3) Set ppservers list to auto-discovery:

ppservers=("*",)

4) Start pp execution server with the number of workers set to the number of processors in the system and list of ppservers to connect with :

job_server = pp.Server(ppservers=ppservers)

5) Submit all the tasks for parallel execution:

f1 = job_server.submit(func1, args1, depfuncs1, modules1)

f2 = job_server.submit(func1, args2, depfuncs1, modules1)

f3 = job_server.submit(func2, args3, depfuncs2, modules2)

...etc...

6) Retrieve the results as needed:

r1 = f1()

r2 = f2()

r3 = f3()

...etc...

To find out how to achieve efficient parallelization with pp please take a look at examples


Advanced guide, clusters

On the nodes

1) Start parallel python execution server on all your remote computational nodes (listen to a given port 35000,
and local network interface only, accept only connections which know correct secret):

node-1> ./ppserver.py -p 35000 -i 192.168.0.101 -s "mysecret"

node-2> ./ppserver.py -p 35000 -i 192.168.0.102 -s "mysecret"

node-3> ./ppserver.py -p 35000 -i 192.168.0.103 -s "mysecret"

On the client

2) Import pp module:

import pp

3) Create a list of all the nodes in your cluster (computers where you've run ppserver.py)

ppservers=("node-1:35000", "node-2:35000", "node-3:35000")

4) Start pp execution server with the number of workers set to the number of processors in the system,
list of ppservers to connect with and secret key to authorize the connection:

job_server = pp.Server(ppservers=ppservers, secret="mysecret")

5) Submit all the tasks for parallel execution:

f1 = job_server.submit(func1, args1, depfuncs1, modules1)

f2 = job_server.submit(func1, args2, depfuncs1, modules1)

f3 = job_server.submit(func2, args3, depfuncs2, modules2)

...etc...

6) Retrieve the results as needed:

r1 = f1()

r2 = f2()

r3 = f3()

...etc...

7) Print the execution statistics:

job_server.print_stats()

To find out how to achieve efficient parallelization with pp please take a look at examples


Command line options, ppserver.py

Usage: ppserver.py [-hda] [-i interface] [-b broadcast] [-p port] [-w nworkers] [-s secret] [-t seconds]
Options:
-h : this help message
-d : debug
-a : enable auto-discovery service
-i interface : interface to listen
-b broadcast : broadcast address for auto-discovery service
-p port : port to listen
-w nworkers : number of workers to start
-s secret : secret for authentication
-t seconds : timeout to exit if no connections with clients exist
-k seconds : socket timeout in seconds
-P pid_file : file to write PID to

Security and secret key

Due to the security concerns it is highly recommended to run ppserver.py with an non-trivial secret key (-s command line argument) which should be paired with the matching secret keyword of PP Server class constructor. Since PP 1.5.3 it is possible to set secret key by assigning pp_secret variable in the configuration file .pythonrc.py which should be located in the user home directory (please make this file readable and writable only by user). The key set in .pythonrc.py could be overridden by command line argument (for ppserver.py) and secret keyword (for PP Server class constructor).


ppserver.py stats and PID file example

To print job execution statistics for ppserver.py send a SIGUSR1 signal to its main process.
For instance on UNIX platform following commands will start a server and print its stats:
ppserver.py -P /tmp/ppserver.pid

kill -s SIGUSR1 `cat /tmp/ppserver.pid`

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