Task handler raised error: ValueError('not enough values to unpack (expected 3, got 0)')
阿新 • • 發佈：2020-08-26
原文出處：
Celery ValueError: not enough values to unpack (expected 3, got 0)的解決方案
背景
最近因專案需要，學習任務佇列Celery的用法，跟著官網寫Demo，出現如題錯誤，最終在github的Issues裡找到解決辦法，記錄如下。
場景還原
本地環境如下：
- Windows 10
- Python 3.5.2
- Celery 4.1.0
我是跟著這個前人翻譯的中文文件敲的Demo。
程式碼tasks.py：
from celery import Celery app = Celery('tasks', broker='redis://:[email protected]:6379/0') @app.task def add(x, y): return x + y
執行worker
celery -A tasks worker --loglevel=info
輸出：
-------------- celery@kong9wei11 v4.1.0 (latentcall) ---- **** ----- --- * *** * -- Windows-10-10.0.14393-SP0 2018-01-12 19:01:39 -- * - **** --- - ** ---------- [config] - ** ---------- .> app: tasks:0x157fd248550- ** ---------- .> transport: redis://:**@114.67.225.0:6379/0 - ** ---------- .> results: disabled:// - *** --- * --- .> concurrency: 4 (prefork) -- ******* ---- .> task events: OFF (enable -E to monitor tasks in this worker) --- ***** ----- -------------- [queues] .> celery exchange=celery(direct) key=celery [tasks] . tasks.add [2018-01-12 19:01:40,029: INFO/MainProcess] Connected to redis://:**@114.67.225.0:6379/0 [2018-01-12 19:01:40,130: INFO/MainProcess] mingle: searching for neighbors [2018-01-12 19:01:40,550: INFO/SpawnPoolWorker-1] child process 9048 calling self.run() [2018-01-12 19:01:40,557: INFO/SpawnPoolWorker-2] child process 9028 calling self.run() [2018-01-12 19:01:40,578: INFO/SpawnPoolWorker-3] child process 13064 calling self.run() [2018-01-12 19:01:40,611: INFO/SpawnPoolWorker-4] child process 9856 calling self.run() [2018-01-12 19:01:41,693: INFO/MainProcess] mingle: all alone [2018-01-12 19:01:42,212: INFO/MainProcess] celery@xx ready.
呼叫任務程式碼manager.py：
from tasks import add add.delay(4, 4)
執行
python manager.py
然後worker裡報錯：
[2018-01-12 19:08:15,545: INFO/MainProcess] Received task: tasks.add[5d387722-5389-441b-9b01-a619b93b4702] [2018-01-12 19:08:15,550: ERROR/MainProcess] Task handler raised error: ValueError('not enough values to unpack (expected 3, got 0)',) Traceback (most recent call last): File "d:\programmingsoftware\python35\lib\site-packages\billiard\pool.py", line 358, in workloop result = (True, prepare_result(fun(*args, **kwargs))) File "d:\programmingsoftware\python35\lib\site-packages\celery\app\trace.py", line 525, in _fast_trace_task tasks, accept, hostname = _loc ValueError: not enough values to unpack (expected 3, got 0)
解決：
原網頁:Unable to run tasks under Windows
看別人描述大概就是說win10上執行celery4.x就會出現這個問題，解決辦法如下,原理未知：
先安裝一個`eventlet
pip install eventlet
然後啟動worker的時候加一個引數，如下：
celery -A <mymodule> worker -l info -P eventlet
然後就可以正常的呼叫了。
執行
python manage.py
worker裡輸出：
[2018-01-12 19:35:33,640: INFO/MainProcess] Received task: tasks.add[3f9b5255-60a2-4a08-96b6-38f5fbc31543] [2018-01-12 19:35:33,640: INFO/MainProcess] Task tasks.add[3f9b5255-60a2-4a08-96b6-38f5fbc31543] succeeded in 0.0s: 8