Decrement clients_requesting_changes in a timely fashion
Decrement clients_requesting_changes in a timely fashion

The previous approach using process_tracker was flawed. If a client
reuses a connection, as is common, the clients_requesting_changes
metric will only be decremented when the connection is terminated,
even if the connection is not requesting changes.

fkaempfer/couchdb,ngpestelos/couchdb-couch,ngpestelos/couchdb-couch,fkaempfer/couchdb,alanning/couchdb-couch,smithsz/couchdb-couch,apache/couchdb-couch,KlausTrainer/couchdb-couch,fkaempfer/couchdb,cloudant/couchdb-couch,KlausTrainer/couchdb-couch,cloudant/couchdb-couch,smithsz/couchdb-couch,KlausTrainer/couchdb-couch,fkaempfer/couchdb,ngpestelos/couchdb-couch,alanning/couchdb-couch,fkaempfer/couchdb,apache/couchdb-couch,apache/couchdb-couch,fkaempfer/couchdb,cloudant/couchdb-couch,alanning/couchdb-couch,smithsz/couchdb-couch