Django 获取facebook图片时芹菜任务错误

我有以下芹菜任务：

@task
def get_users_facebook_as_profile_icon(user_id, facebook_id):
    logger.info('Grabbing users facebook picture')
    url = "http://graph.facebook.com/%s/picture?type=large" % facebook_id

    import requests
    response = requests.get(url)
    if response.status_code != 200:
        raise Exception("Could not get facebook profile picture")
...

在这之后，我有了更多，但我一直得到以下错误：

"AssertionError('PID check failed. RNG must be re-initialized after fork(). Hint: Try Random.atfork()',)" 


Task was called with args: (3246, 17500596) kwargs: {}. 

The contents of the full traceback was: 

Traceback (most recent call last): 
File "/usr/local/lib/python2.7/dist-packages/celery/app/trace.py", line 240, in trace_task 
R = retval = fun(*args, **kwargs) 
File "/usr/local/lib/python2.7/dist-packages/celery/app/trace.py", line 437, in __protected_call__ 
return self.run(*args, **kwargs) 
File "/home/ubuntu/mounzawebsite/mounza/celery_tasks/login_registration.py", line 42, in get_users_facebook_as_profile_icon 
hashname = user.generate_picture_name() 
File "/home/ubuntu/mounzawebsite/mounza/web/models.py", line 515, in generate_picture_name 
return generate_random_name(None) 
File "/home/ubuntu/mounzawebsite/mounza/web/models.py", line 40, in generate_random_name 
str(random.randint(1, 99982098098908237)) + 
File "/usr/lib/python2.7/dist-packages/Crypto/Random/__init__.py", line 41, in get_random_bytes 
return _UserFriendlyRNG.get_random_bytes(n) 
File "/usr/lib/python2.7/dist-packages/Crypto/Random/_UserFriendlyRNG.py", line 213, in get_random_bytes 
return _get_singleton().read(n) 
File "/usr/lib/python2.7/dist-packages/Crypto/Random/_UserFriendlyRNG.py", line 163, in read 
return _UserFriendlyRNG.read(self, bytes) 
File "/usr/lib/python2.7/dist-packages/Crypto/Random/_UserFriendlyRNG.py", line 122, in read 
self._check_pid() 
File "/usr/lib/python2.7/dist-packages/Crypto/Random/_UserFriendlyRNG.py", line 138, in _check_pid 
raise AssertionError("PID check failed. RNG must be re-initialized after fork(). Hint: Try Random.atfork()") 
AssertionError: PID check failed. RNG must be re-initialized after fork(). Hint: Try Random.atfork() 

我试着在网上深入研究，却找不到根本原因。但这是唯一发生此错误的任务。唯一的区别是我从Facebook下载了一张图片，但我从来没有在其他地方看到过这个问题，包括我下载图片的其他任务

如果我通过web浏览器来访问URL，它会工作得很好，但只有通过这个任务它才会失败。还有什么其他原因可能导致这种情况吗

我已经用尽了所有的努力来解决这个问题：

以下是原因：

始终运行以下各项：

Crypto.Random.atfork()

初始化新工作进程时。做了，做了