将System.out.println或stdout数据捕获到摆动备忘录（巨大数据）(Capturing System.out.println or stdout data to a swing memo (Huge Data))

 SessionMiddleware的第三行调用一个特定的会话引擎 ，它决定了要使用哪个SessionStore。 
 
 如果您进入contrib / sessions / backends / base.py，您将看到以下代码： 
 
class SessionBase(object):

    ...

    def __getitem__(self, key):
        return self._session[key]

    def _get_session(self, no_load=False):
        """
        Lazily loads session from storage (unless "no_load" is True, when only
        an empty dict is stored) and stores it in the current instance.
        """
        self.accessed = True
        try:
            return self._session_cache
        except AttributeError:
            if self._session_key is None or no_load:
                self._session_cache = {}
            else:
                self._session_cache = self.load()
        return self._session_cache

    _session = property(_get_session)
 
 它所做的是创建一个会话代理对象，中间件已附加到该请求。 它不会从数据库加载会话对象，直到您说出： 
 
x = request.session['key']
 
 此时， __getitem__(self, key) self._session __getitem__(self, key)试图解引用self._session ，它（作为属性）反过来返回此事务的会话字典的缓存副本，或者如果没有可用的缓存，则从存储中获取它使用load()方法。 load()方法由特定的子引擎实现：数据库，文件，缓存，缓存+数据库等。 
 
 SessionStore是一个完整会话的轻量级代理; 当您需要读取或写入与会话ID cookie中编码的密钥关联的会话对象的数据时，它只会变成一个完整的会话，触及数据库。 

The third line of SessionMiddleware invokes a specific session engine, which dictates which SessionStore to use. 
 
If you go down into contrib/sessions/backends/base.py, you'll see the following code:
 
class SessionBase(object):

    ...

    def __getitem__(self, key):
        return self._session[key]

    def _get_session(self, no_load=False):
        """
        Lazily loads session from storage (unless "no_load" is True, when only
        an empty dict is stored) and stores it in the current instance.
        """
        self.accessed = True
        try:
            return self._session_cache
        except AttributeError:
            if self._session_key is None or no_load:
                self._session_cache = {}
            else:
                self._session_cache = self.load()
        return self._session_cache

    _session = property(_get_session)
 
What this does is create a session proxy object, which the middleware has attached to the request. It does not load the session object from the database until you say:
 
x = request.session['key']
 
At which point, the __getitem__(self, key) attempts to dereference self._session, which (being a property) in turn returns a cached copy of the session dictionary for this transaction, or if no cache is available, fetches it from the store using the load() method. The load() method is implemented by specific child engines: database, file, cache, cache + db, etc. 
 
SessionStore is a lightweight proxy for a full session; it only becomes a full session, hitting the database, when you need to read or write data to the session object associated with the key encoded in the session id cookie.