Topology information is loaded by using Composite operations. A composite operation could require the write lock on the DC when there is more than one slave in the domain. In this scenario, the DC's write lock is acquired until the overall operation, which is being executed in DC and in all the slaves, finishes.

If there is another operation being executed in the DC that previously has acquired the write lock, e.g servers in the domain are being started or an application is being deployed, the topology won't be able to load.