Celery Django 調用.delay() 后任務掛起

Question

從 django 應用程序調用導入任務的.delay()方法時，進程卡住，請求永遠不會完成。

我們也沒有在控制台上收到任何錯誤。 使用 pdb 設置set_trace()會產生同樣的結果。

審查了以下問題，但沒有幫助解決問題：

調用celery任務掛起延遲和apply_async

celery.delay 掛起（最近，不是身份驗證問題）

例如。：

后端/settings.py

CELERY_BROKER_URL = os.environ.get("CELERY_BROKER", RABBIT_URL)
CELERY_RESULT_BACKEND = os.environ.get("CELERY_BROKER", RABBIT_URL)

后端/celery.py

from __future__ import absolute_import, unicode_literals

import os

from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'backend.settings')

app = Celery('backend')

app.config_from_object('django.conf:settings', namespace='CELERY')

# Load task modules from all registered Django app configs.
app.autodiscover_tasks()


@app.task(bind=True)
def debug_task(self):
    print('Request: {0!r}'.format(self.request))

應用程序/tasks.py

import time
from celery import shared_task

@shared_task
def upload_file(request_id):
    time.sleep(request_id)
    return True

應用程序/views.py

from rest_framework.views import APIView

from .tasks import upload_file

class UploadCreateAPIView(APIView):
    # other methods...

    def post(self, request, *args, **kwargs):
        id = request.data.get("id", None)
        # business logic ...
        print("Going to submit task.")
        import pdb; pdb.set_trace()
        upload_file.delay(id)                  # <- this hangs the runserver as well as the set_trace()
        print("Submitted task.")

Answer 1

問題在於使用 Django 設置 celery 應用程序。 我們需要確保在以下文件中導入並初始化了 celery 應用程序：

backend\\__init__.py

from __future__ import absolute_import, unicode_literals

# This will make sure the app is always imported when
# Django starts so that shared_task will use this app.
from .celery import app as celery_app

__all__ = ('celery_app',)

Answer 2

我遇到過這個問題，即 Celery 通過delay或apply_async調用可能會無限期地隨機掛起程序。 我嘗試了所有broker_transport_options和retry_policy選項讓 Celery 恢復，但它仍然發生。 然后我發現這個解決方案通過使用底層 Python 信號處理程序來強制執行塊/函數的執行時間限制。

@contextmanager
def time_limit(seconds):
    def signal_handler(signum, frame):
        raise TimeoutException("Timed out!")

    signal.signal(signal.SIGALRM, signal_handler)
    signal.alarm(seconds)
    try:
        yield
    finally:
        signal.alarm(0)

def my_function():
    with time_limit(3):
        celery_call.apply_sync(kwargs={"k1", "v1"}, expires=30)