sd/etcdv3 keepalive channel not served

[fangdingjun]

kit/sd/etcdv3/client.go

Line 202 in e0e1b24

c.hbch, err = c.leaser.KeepAlive(c.ctx, c.leaseID)

the channel c.hbch not served, etcd library print a lots of log like this, every 3 seconds

{"level":"warn","ts":1542791960.4143248,"caller":"clientv3/lease.go:524","msg":"lease keepalive response queue is full; dropping response send","queue-size":16,"queue-capacity":16}
{"level":"warn","ts":1542791963.92008,"caller":"clientv3/lease.go:524","msg":"lease keepalive response queue is full; dropping response send","queue-size":16,"queue-capacity":16}
{"level":"warn","ts":1542791967.4572115,"caller":"clientv3/lease.go:524","msg":"lease keepalive response queue is full; dropping response send","queue-size":16,"queue-capacity":16}