These changes cause the hub to use generators for some potentially large
queries internally. The point is to reduce memory usage.
In the case that a large query is returned via rpc, the marshaller has
been extended to handle generators. The marshaller will still create a
giant pile of xml, but we at least still save the memory for the
I also have some work on an iterating marshaller that will not keep the
entire xml return in memory, but that's a bit more complicated, so I'm
going to leave that for another day.
There are other cases (e.g. repo_init) where we have very large queries
internally. In these cases, this patch set will result in significant