如何在GAE中有效实施会话？

I was wondering about implementing my own sessions (more for an exercise than anything else) for a GAE app I'm working ... at first I was thinking of using the datastore to store the session data. However, every time something needs to be added to the session 'bucket', it would require saving to the datastore. Obviously that's bad since we want to minimize our writes. Then I thought about using memcache ... seemed like a good idea but then we're faced with issues of possible session corruption due to memcache being "evicted through memory pressure" by Google. So does that mean we are left with only the following options:I was wondering about implementing my own sessi