Running show measurements in a partially replicated cluster produces inconsistent
results due to the connection pooling. When running remote meta-data queries,
the cluster service ends ups keeping map shard request open but still checks the connection
back into the pool. This causes inconsistent results because data from the last request
interferes with the new request.
This removes the connection pool which fixes the issue. It also has the side effect of fixing
a nodes pool connections that have gone bad when a node restarts. For example, in a 3 node cluster
that has been responding to queries correctly, restarting 1 node will cause all the other to fail
to query that node indefinitely. This is now fixed as well.
Some nodes may receive requests for shards that they are assigned but
do not have the shards locally yet. Just return no results in this case
instead of panicing.
David Norton
Ben Johnson
Cory LaNou
Jason Wilder