ZODB Mountpoint Deadlock

[Dieter Maurer]

"Products.ZODBMountPoint.Mount.MountPoint._getMountedConnection"
(and friends) take a connection out of the mounted database's pool
and associates it permanently with the root connection (performing the mount).

This can lead to a (partial) deadlock, when the pool size
of the root database is larger than that of a mounted database
(all available mounted connections are fixed in root connections
and a new root connection tries to mount the database).

It would be more natural, to open mounted connections "temporary",
as they are managed in the containing root connection and
not the database's pool.

A related bug: a "mounted" connection is never released
even when the mounting root database is closed.
This is because there is no "_breakcr" patch, that would take care
of mounted connections.

[Colin Watson (cjwatson)]

The zope2 project on Launchpad has been archived at the request of the Zope developers (see https://answers.launchpad.net/launchpad/+question/683589 and https://answers.launchpad.net/launchpad/+question/685285). If this bug is still relevant, please refile it at https://github.com/zopefoundation/zope2.