from concurrent.futures import ThreadPoolExecutor
import copy
import os
import logging
from tqdm import tqdm
from typing import List
from .base import Engine
from .task import Task
logger = logging.getLogger(__name__)
def work(task):
"""Just execute task."""
return task.execute()
[docs]class MultiThreadEngine(Engine):
"""
Parallelize the task execution using multithreading.
Parameters
----------
n_threads:
The maximum number of threads to use in parallel.
Defaults to the number of CPUs available on the system according to
`os.cpu_count()`.
The effectively used number of threads will be the minimum of
`n_threads` and the number of tasks submitted.
"""
[docs] def __init__(self, n_threads: int = None):
super().__init__()
if n_threads is None:
n_threads = os.cpu_count()
logger.warning(
f"Engine set up to use up to {n_threads} processes in total. "
f"The number was automatically determined and might not be "
f"appropriate on some systems.")
self.n_threads: int = n_threads
[docs] def execute(self, tasks: List[Task], progress_bar: bool = True):
"""Deepcopy tasks and distribute work over parallel threads.
Parameters
----------
tasks:
List of tasks to execute.
progress_bar:
Whether to display a progress bar.
"""
n_tasks = len(tasks)
copied_tasks = [copy.deepcopy(task) for task in tasks]
n_threads = min(self.n_threads, n_tasks)
logger.info(f"Performing parallel task execution on {n_threads} "
f"threads.")
with ThreadPoolExecutor(max_workers=n_threads) as pool:
results = pool.map(work,
tqdm(copied_tasks,
disable=not progress_bar)
)
return results