A package for easy task parallelization across CPU threads
Project description
mpyll
mpyll is a package for easy task parallelization across CPU threads.
Installation
pip install mpyll
Usage
mpyll logic is as follows:
- Identify the data on which to parallelize computation. The data should be stored in a list.
- Define the task: a python function that takes as input a list of data elements and performs the desired task. This is the parallelized task; instances of this function are to be running in CPU threads.
- Define an eventual post processing function that takes as input a list of data and returns the final result, if any.
Example
Let's take as an example the estimation of Pi through Monte Carlo:
# First, we define the data on which we would like to parallelize computation.
r = 1.
m = 10 ** 6
X = np.random.uniform(-r, r, size = m)
Y = np.random.uniform(-r, r, size = m)
data = [(X[i], Y[i]) for i in range(m)]
# Second, we define the task to be parallelized.
# It takes as input the data (a list) as well as other arguments, if any,
# and it returns a result. If it is a procedure, then it does not return.
def count_in_circle_points(data, r, m):
a = np.array(data) # matrix, each row contains a point coordinates
d = np.sqrt(np.sum(a ** 2, axis = 1)) # distance to the origin
in_circle = d <= r # an array, True if distance <= radius, False otherwise
return np.sum(in_circle)
# Finally, we define a post processor.
def estimate_pi(data, m):
pi_estimation = 4 * np.sum(data) / m
return pi_estimation
pi_estimation = parallelize(task = count_in_circle_points,
data = data, data_shuffle = False,
post_processor = estimate_pi,
n_jobs = -1,
# task arguments
count_in_circle_points_r = r,
count_in_circle_points_m = m,
# post processor arguments
estimate_pi_m = m)
API
parallelize(task,
data,
shuffle_data = False,
post_processor = None,
n_jobs = -1,
*args,
**kwargs)
Parallelize a task that returns a value
Parameters
----------
task: function
The task to be parallelized.
data: list
The data on which the parallelization is performed.
shuffle\_data: boolean
shuffle data before processing. Sometimes the data are not identically
distributed, which could cause some threads to be overloaded compared to
others.
post\_processor: function
A function that runs after all threads terminate.
n\_jobs: int
The number of threads to be used. Specify -1 to use all CPU threads.
Other Parameters
----------------
Other parameters could be passed to `task` and `post_processor`. The argument
name should start with the name of the task or the post processor, followed
by an underscore, then followed by the name of the argument.
Returns
-------
If a post processor is specified, then this function returns what is returned
by the post processor, otherwise, it returns a list of the objects returned by
each thread.
License
GNU General Public License v3
Project details
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