4
我的同事要求我的幫助,他遇到了一個他正在使用的守護進程腳本的問題。他是有一個奇怪的錯誤涉及multiprocessing.Manager,我成功地再現與以下五類線:Python multiprocessing.manager和os.fork產生奇怪的行爲
import multiprocessing, os, sys
mgr = multiprocessing.Manager()
pid = os.fork()
if pid > 0:
sys.exit(0)
當在CentOS 6 Linux和Python 2.6中運行時,我收到以下錯誤:
Traceback (most recent call last):
File "/usr/lib64/python2.6/multiprocessing/util.py", line 235, in _run_finalizers
finalizer()
File "/usr/lib64/python2.6/multiprocessing/util.py", line 174, in __call__
res = self._callback(*self._args, **self._kwargs)
File "/usr/lib64/python2.6/multiprocessing/managers.py", line 576, in _finalize_manager
if process.is_alive():
File "/usr/lib64/python2.6/multiprocessing/process.py", line 129, in is_alive
assert self._parent_pid == os.getpid(), 'can only test a child process'
AssertionError: can only test a child process
Error in atexit._run_exitfuncs:
Traceback (most recent call last):
File "/usr/lib64/python2.6/atexit.py", line 24, in _run_exitfuncs
func(*targs, **kargs)
File "/usr/lib64/python2.6/multiprocessing/util.py", line 269, in _exit_function
p.join()
File "/usr/lib64/python2.6/multiprocessing/process.py", line 117, in join
assert self._parent_pid == os.getpid(), 'can only join a child process'
AssertionError: can only join a child process
Error in sys.exitfunc:
Traceback (most recent call last):
File "/usr/lib64/python2.6/atexit.py", line 24, in _run_exitfuncs
func(*targs, **kargs)
File "/usr/lib64/python2.6/multiprocessing/util.py", line 269, in _exit_function
p.join()
File "/usr/lib64/python2.6/multiprocessing/process.py", line 117, in join
assert self._parent_pid == os.getpid(), 'can only join a child process'
AssertionError: can only join a child process
我懷疑這個錯誤是由os.fork和multiprocessing.Manager之間的一些交互造成的,他應該使用多處理模塊來創建新的進程而不是os.fork。任何人都可以證實這一點和/或解釋發生了什麼?如果我的預感是正確的,爲什麼這是錯誤的地方使用os.fork?
'Manager'總是創建一個處理共享內存的新進程,所以似乎有一些交互。現在我無法確切地告訴你爲什麼會發生這種情況,以及如何使用'os.fork'來解決這個問題。我必須同意,應該避免使用'os.fork',因爲它真的是*低級*。應該有一些使用'multiprocessing'的方法。 – Bakuriu