从第三方应用程序导入视图时，Django 应用程序抛出虚假异常

Question

我正在开发一个 Django 应用程序，当尝试从第三方应用程序（具体来说，Solango）导入模块时，该应用程序偶尔会引发 ViewDoesNotExist 异常。我所说的“偶尔”是指经常令人厌烦，但绝对是少数请求。 Solango 位于应用的 PYTHONPATH 上，可以通过控制台可靠地导入。该错误在本地开发期间也从未发生过，因此可能与服务器设置有关（该应用程序在守护进程模式下使用 Apache + mod_wsgi）。

这是一个堆栈跟踪，显示了管理中发生的错误（尽管它几乎发生在网站的每个页面上）：

Traceback:
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/handlers/base.py" in get_response
  92.                 response = callback(request, *callback_args, **callback_kwargs)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/contrib/admin/sites.py" in root
  445.             return self.index(request)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  44.         response = view_func(request, *args, **kwargs)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/contrib/admin/sites.py" in index
  342.             context_instance=template.RequestContext(request)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/shortcuts/__init__.py" in render_to_response
  20.     return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/loader.py" in render_to_string
  108.     return t.render(context_instance)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  178.         return self.nodelist.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/loader_tags.py" in render
  97.         return compiled_parent.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  178.         return self.nodelist.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/loader_tags.py" in render
  97.         return compiled_parent.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  178.         return self.nodelist.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/defaulttags.py" in render
  245.                     return self.nodelist_true.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/defaulttags.py" in render
  255.             return self.nodelist_true.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/loader_tags.py" in render
  24.         result = self.nodelist.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render
  778.                 bits.append(self.render_node(node, context))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/__init__.py" in render_node
  791.         return node.render(context)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/template/defaulttags.py" in render
  372.             url = reverse(self.view_name, args=args, kwargs=kwargs)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/urlresolvers.py" in reverse
  265.             *args, **kwargs)))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/urlresolvers.py" in reverse
  238.         possibilities = self.reverse_dict.getlist(lookup_view)
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/urlresolvers.py" in _get_reverse_dict
  165.                     for name in pattern.reverse_dict:
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/urlresolvers.py" in _get_reverse_dict
  173.                     lookups.appendlist(pattern.callback, (bits, p_pattern))
File "/home/nybooks/ve/lib/python2.5/site-packages/django/core/urlresolvers.py" in _get_callback
  134.             raise ViewDoesNotExist, "Could not import %s. Error was: %s" % (mod_name, str(e))

Exception Type: ViewDoesNotExist at /admin/
Exception Value: Could not import solango.views. Error was: cannot import name settings

关于导致问题的原因，或者至少我如何调试它，有什么想法吗？

Answer 1

您的网络服务器没有文件描述符。重新配置 mod_wsgi 为守护进程模式。

Answer 2

导入的代码可能具有顺序依赖性。这不会出现在开发服务器中，因为预加载了很多不在生产 WSGI 服务器下的内容。

所以最终就像你如何使用 Django 一样。在此期间，您可以尝试以下建议：

http://blog.dscpl.com.au/2010/03/improved-wsgi-script-for-use-with.html

获取 WSGI 脚本文件的替代内容，看看问题是否消失。