From 5f3891af303883ca7c2b0badcf4a2ba27d2dcb3e Mon Sep 17 00:00:00 2001
From: Gyu-Ho Lee <gyuhox@gmail.com>
Date: Fri, 14 Jul 2017 13:26:58 -0700
Subject: [PATCH] embed: wait up to 10s for pending RPCs when closing

Both grpc.Server.Stop and grpc.Server.GracefulStop close the listeners
first, to stop accepting the new connections. GracefulStop blocks until
all clients close their open transports(connections). Unary RPCs
only take a few seconds to finish. Stream RPCs, like watch, might never
close the connections from client side, thus making gRPC server wait
forever.

This patch still calls GracefulStop, but waits up to 10s before manually
closing the open transports.

Address https://github.com/coreos/etcd/issues/8224.

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
---
 embed/etcd.go | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/embed/etcd.go b/embed/etcd.go
index 64fbfac702a5..e3ce0ba940ea 100644
--- a/embed/etcd.go
+++ b/embed/etcd.go
@@ -189,11 +189,25 @@ func (e *Etcd) Config() Config {
 func (e *Etcd) Close() {
 	e.closeOnce.Do(func() { close(e.stopc) })
 
-	// (gRPC server) stops accepting new connections,
-	// RPCs, and blocks until all pending RPCs are finished
 	for _, sctx := range e.sctxs {
 		for gs := range sctx.grpcServerC {
-			gs.GracefulStop()
+			ch := make(chan struct{})
+			go func() {
+				defer close(ch)
+				// close listeners to stop accepting new connections,
+				// will block on any existing transports
+				gs.GracefulStop()
+			}()
+			// wait until all pending RPCs are finished
+			select {
+			case <-ch:
+			case <-time.After(10 * time.Second):
+				// took too long, manually close open transports
+				// e.g. watch streams
+				gs.Stop()
+				// concurrent GracefulStop should be interrupted
+				<-ch
+			}
 		}
 	}