Memcache flush_all not working as expected with namespaces on Google App Engine Python

1
votes

Going over the documentation for multitenancy + memcache it seems that memcache entries are separated for each namespace. See documentation here.

The problem is that when we call:

memcache.flush_all()

Everything is flushed in the memcache, not just the entries for the current namespace.

Before calling flush_all() we are explicitly setting the namespace using the following code:

namespace_manager.set_namespace(foo)

How can I flush entries in memcache only for the current namespace?

1
google-app-engine
I don't believe it's possible. All the namespace is doing is adding information to the keys, so you don't have to do it in your code. - Tim Hoffman

1 Answers

1
votes

Yes, it is somewhat unexpected that flush_all deletes everything in your app's memcache not just for one namespace. The App Engine development team has a feature request to allow per-namespace flushing. See Issue 5190.

One workaround is for you to maintain a persistent integer "generation count" that you include as part of the namespace name. When you want to flush a namespace, you instead increment the generation count and use the new namespace, which will be brand new and empty. You can ignore the items in your old namespace, as they will slowly get evicted over time.