diff --git a/client/rpc_pool.go b/client/rpc_pool.go
index 7fa0e720..7bdf6929 100644
--- a/client/rpc_pool.go
+++ b/client/rpc_pool.go
@@ -63,6 +63,7 @@ func (p *pool) release(addr string, conn *poolConn, err error) {
 	p.Lock()
 	conns := p.conns[addr]
 	if len(conns) >= maxIdleConn {
+		p.Unlock()
 		conn.Client.Close()
 		return
 	}