We had a rare deadlock in GetOrHandshake because we kept the hostmap lock when we do the call to StartHandshake. StartHandshake can block while sending to the lighthouse query worker channel, and that worker needs to be able to grab the hostmap lock to do its work. Other calls for StartHandshake don't hold the hostmap lock so we should be able to drop it here.
We had a rare deadlock in GetOrHandshake because we kept the hostmap lock when we do the call to StartHandshake. StartHandshake can block while sending to the lighthouse query worker channel, and that worker needs to be able to grab the hostmap lock to do its work. Other calls for StartHandshake don't hold the hostmap lock so we should be able to drop it here.
This lock was originally added with: https://github.com/slackhq/nebula/pull/954