add interval refresh of running/killed containers in map

collector/docker.go

@@ -33,6 +33,8 @@ func NewDocker(client *api.Client, id string) *Docker {
 	}()
 
 	go func() {
+		defer close(stats)
+		defer close(c.stream)
 		for s := range stats {
 			c.ReadCPU(s)
 			c.ReadMem(s)