Joshua Lochner
Add compatibility for python 3.6+
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import re
import os
import signal
import logging
import sys
from time import sleep, time
from random import random, randint
from multiprocessing import JoinableQueue, Event, Process
from queue import Empty
from typing import Optional
logger = logging.getLogger(__name__)
def re_findall(pattern, string):
return [m.groupdict() for m in re.finditer(pattern, string)]
class Task:
def __init__(self, function, *args, **kwargs) -> None:
self.function = function
self.args = args
self.kwargs = kwargs
def run(self):
return self.function(*self.args, **self.kwargs)
class CallbackGenerator:
def __init__(self, generator, callback):
self.generator = generator
self.callback = callback
def __iter__(self):
if self.callback is not None and callable(self.callback):
for t in self.generator:
self.callback(t)
yield t
else:
yield from self.generator
def start_worker(q: JoinableQueue, stop_event: Event): # TODO make class?
logger.info('Starting worker...')
while True:
if stop_event.is_set():
logger.info('Worker exiting because of stop_event')
break
# We set a timeout so we loop past 'stop_event' even if the queue is empty
try:
task = q.get(timeout=.01)
except Empty:
# Run next iteration of loop
continue
# Exit if end of queue
if task is None:
logger.info('Worker exiting because of None on queue')
q.task_done()
break
try:
task.run() # Do the task
except: # Will also catch KeyboardInterrupt
logger.exception(f'Failed to process task {task}', )
# Can implement some kind of retry handling here
finally:
q.task_done()
class InterruptibleTaskPool:
# https://the-fonz.gitlab.io/posts/python-multiprocessing/
def __init__(self,
tasks=None,
num_workers=None,
callback=None, # Fired on start
max_queue_size=1,
grace_period=2,
kill_period=30,
):
self.tasks = CallbackGenerator(
[] if tasks is None else tasks, callback)
self.num_workers = os.cpu_count() if num_workers is None else num_workers
self.max_queue_size = max_queue_size
self.grace_period = grace_period
self.kill_period = kill_period
# The JoinableQueue has an internal counter that increments when an item is put on the queue and
# decrements when q.task_done() is called. This allows us to wait until it's empty using .join()
self.queue = JoinableQueue(maxsize=self.max_queue_size)
# This is a process-safe version of the 'panic' variable shown above
self.stop_event = Event()
# n_workers: Start this many processes
# max_queue_size: If queue exceeds this size, block when putting items on the queue
# grace_period: Send SIGINT to processes if they don't exit within this time after SIGINT/SIGTERM
# kill_period: Send SIGKILL to processes if they don't exit after this many seconds
# self.on_task_complete = on_task_complete
# self.raise_after_interrupt = raise_after_interrupt
def __enter__(self):
self.start()
return self
def __exit__(self, exc_type, exc_value, exc_traceback):
pass
def start(self) -> None:
def handler(signalname):
"""
Python 3.9 has `signal.strsignal(signalnum)` so this closure would not be needed.
Also, 3.8 includes `signal.valid_signals()` that can be used to create a mapping for the same purpose.
"""
def f(signal_received, frame):
raise KeyboardInterrupt(f'{signalname} received')
return f
# This will be inherited by the child process if it is forked (not spawned)
signal.signal(signal.SIGINT, handler('SIGINT'))
signal.signal(signal.SIGTERM, handler('SIGTERM'))
procs = []
for i in range(self.num_workers):
# Make it a daemon process so it is definitely terminated when this process exits,
# might be overkill but is a nice feature. See
# https://docs.python.org/3.8/library/multiprocessing.html#multiprocessing.Process.daemon
p = Process(name=f'Worker-{i:02d}', daemon=True,
target=start_worker, args=(self.queue, self.stop_event))
procs.append(p)
p.start()
try:
# Put tasks on queue
for task in self.tasks:
logger.info(f'Put task {task} on queue')
self.queue.put(task)
# Put exit tasks on queue
for i in range(self.num_workers):
self.queue.put(None)
# Wait until all tasks are processed
self.queue.join()
except KeyboardInterrupt:
logger.warning('Caught KeyboardInterrupt! Setting stop event...')
# raise # TODO add option
finally:
self.stop_event.set()
t = time()
# Send SIGINT if process doesn't exit quickly enough, and kill it as last resort
# .is_alive() also implicitly joins the process (good practice in linux)
while True:
alive_procs = [p for p in procs if p.is_alive()]
if not alive_procs:
break
if time() > t + self.grace_period:
for p in alive_procs:
os.kill(p.pid, signal.SIGINT)
logger.warning(f'Sending SIGINT to {p}')
elif time() > t + self.kill_period:
for p in alive_procs:
logger.warning(f'Sending SIGKILL to {p}')
# Queues and other inter-process communication primitives can break when
# process is killed, but we don't care here
p.kill()
sleep(.01)
sleep(.1)
for p in procs:
logger.info(f'Process status: {p}')
def jaccard(x1, x2, y1, y2):
# Calculate jaccard index
intersection = max(0, min(x2, y2)-max(x1, y1))
filled_union = max(x2, y2) - min(x1, y1)
return intersection/filled_union if filled_union > 0 else 0