Merge pull request #3385 from hashicorp/issue-3376

Switches to using a read lock for the agent's RPC dispatcher.

CHANGELOG.md

@@ -5,6 +5,8 @@ FEATURES:
 
 IMPROVEMENTS:
 
+* agent: Switched to using a read lock for the agent's RPC dispatcher, which prevents RPC calls from getting serialized. [GH-3376]
+
 BUG FIXES:
 
 ## 0.9.2 (August 9, 2017)

agent/agent.go

@@ -956,7 +956,7 @@ func (a *Agent) registerEndpoint(name string, handler interface{}) error {
 // RPC is used to make an RPC call to the Consul servers
 // This allows the agent to implement the Consul.Interface
 func (a *Agent) RPC(method string, args interface{}, reply interface{}) error {
-	a.endpointsLock.Lock()
+	a.endpointsLock.RLock()
 	// fast path: only translate if there are overrides
 	if len(a.endpoints) > 0 {
 		p := strings.SplitN(method, ".", 2)
@@ -964,7 +964,7 @@ func (a *Agent) RPC(method string, args interface{}, reply interface{}) error {
 			method = e + "." + p[1]
 		}
 	}
-	a.endpointsLock.Unlock()
+	a.endpointsLock.RUnlock()
 	return a.delegate.RPC(method, args, reply)
 }