[英]How to log to single file with multiprocessing.Pool.apply_async
我無法記錄到使用 multprocess.Pool.apply_async 的單個文件。 我正在嘗試改編 Logging Cookbook 中的這個示例,但它僅適用於multiprocessing.Process
。 將日志記錄隊列傳遞到apply_async
似乎沒有效果。 我想使用一個池,以便我可以輕松管理並發線程的數量。
以下采用 multiprocessing.Process 的改編示例對我來說工作正常,除了我沒有從主進程獲取日志消息,而且我認為當我有 100 個大型作業時它不會很好地工作。
import logging
import logging.handlers
import numpy as np
import time
import multiprocessing
import pandas as pd
log_file = 'PATH_TO_FILE/log_file.log'
def listener_configurer():
root = logging.getLogger()
h = logging.FileHandler(log_file)
f = logging.Formatter('%(asctime)s %(processName)-10s %(name)s %(levelname)-8s %(message)s')
h.setFormatter(f)
root.addHandler(h)
# This is the listener process top-level loop: wait for logging events
# (LogRecords)on the queue and handle them, quit when you get a None for a
# LogRecord.
def listener_process(queue, configurer):
configurer()
while True:
try:
record = queue.get()
if record is None: # We send this as a sentinel to tell the listener to quit.
break
logger = logging.getLogger(record.name)
logger.handle(record) # No level or filter logic applied - just do it!
except Exception:
import sys, traceback
print('Whoops! Problem:', file=sys.stderr)
traceback.print_exc(file=sys.stderr)
def worker_configurer(queue):
h = logging.handlers.QueueHandler(queue) # Just the one handler needed
root = logging.getLogger()
root.addHandler(h)
# send all messages, for demo; no other level or filter logic applied.
root.setLevel(logging.DEBUG)
# This is the worker process top-level loop, which just logs ten events with
# random intervening delays before terminating.
# The print messages are just so you know it's doing something!
def worker_function(sleep_time, name, queue, configurer):
configurer(queue)
start_message = 'Worker {} started and will now sleep for {}s'.format(name, sleep_time)
logging.info(start_message)
time.sleep(sleep_time)
success_message = 'Worker {} has finished sleeping for {}s'.format(name, sleep_time)
logging.info(success_message)
def main_with_process():
start_time = time.time()
single_thread_time = 0.
queue = multiprocessing.Queue(-1)
listener = multiprocessing.Process(target=listener_process,
args=(queue, listener_configurer))
listener.start()
workers = []
for i in range(10):
name = str(i)
sleep_time = np.random.randint(10) / 2
single_thread_time += sleep_time
worker = multiprocessing.Process(target=worker_function,
args=(sleep_time, name, queue, worker_configurer))
workers.append(worker)
worker.start()
for w in workers:
w.join()
queue.put_nowait(None)
listener.join()
end_time = time.time()
final_message = "Script execution time was {}s, but single-thread time was {}s".format(
(end_time - start_time),
single_thread_time
)
print(final_message)
if __name__ == "__main__":
main_with_process()
但我無法讓以下適應工作:
def main_with_pool():
start_time = time.time()
queue = multiprocessing.Queue(-1)
listener = multiprocessing.Process(target=listener_process,
args=(queue, listener_configurer))
listener.start()
pool = multiprocessing.Pool(processes=3)
job_list = [np.random.randint(10) / 2 for i in range(10)]
single_thread_time = np.sum(job_list)
for i, sleep_time in enumerate(job_list):
name = str(i)
pool.apply_async(worker_function,
args=(sleep_time, name, queue, worker_configurer))
queue.put_nowait(None)
listener.join()
end_time = time.time()
print("Script execution time was {}s, but single-thread time was {}s".format(
(end_time - start_time),
single_thread_time
))
if __name__ == "__main__":
main_with_pool()
我嘗試了許多細微的變化,使用 multiprocessing.Manager、multiprocessing.Queue、multiprocessing.get_logger、apply_async.get(),但沒有任何工作。
我認為會有一個現成的解決方案。 我應該試試芹菜嗎?
謝謝
考慮使用兩個隊列。 第一個隊列是您為工作人員放置數據的地方。 作業完成后,每個工作人員會將結果推送到第二個隊列。 現在,使用第二個隊列將日志寫入文件。
實際上,這里有兩個相互獨立的問題:
multiprocessing.Queue()
對象作為參數傳遞給基於Pool的函數(可以將其傳遞給直接啟動的工作程序,但不能傳遞給它的任何“進一步”對象)。 None
發送給偵聽器進程。 要修復第一個,請替換:
queue = multiprocessing.Queue(-1)
有:
queue = multiprocessing.Manager().Queue(-1)
因為可以傳遞經理管理的Queue()
實例。
要解決第二個問題,請從每個異步調用收集每個結果,或者關閉池並等待它,例如:
pool.close()
pool.join()
queue.put_nowait(None)
或更復雜的:
getters = []
for i, sleep_time in enumerate(job_list):
name = str(i)
getters.append(
pool.apply_async(worker_function,
args=(sleep_time, name, queue, worker_configurer))
)
while len(getters):
getters.pop().get()
# optionally, close and join pool here (generally a good idea anyway)
queue.put_nowait(None)
(您還應該考慮將put_nowait
替換為等待版本的put
而不要使用無限長度的隊列。)
[附錄] 關於maxtasksperchild=1
你真的不需要它。 重復消息的原因是:您反復向子進程的根記錄器添加queuehandlers
處理程序。 以下代碼在添加另一個處理程序之前檢查是否存在任何處理程序:
def worker_configurer(queue):
root = logging.getLogger()
# print(f'{root.handlers=}')
if len(root.handlers) == 0:
h = logging.handlers.QueueHandler(queue)
root.addHandler(h)
root.setLevel(logging.DEBUG)
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