From 334554f655e2a409792fcee646220658aa4825da 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 request timeout 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 | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/embed/etcd.go b/embed/etcd.go
index 5b7a17ca99a..c5c0d2d699f 100644
--- a/embed/etcd.go
+++ b/embed/etcd.go
@@ -192,11 +192,29 @@ 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
+	timeout := 2 * time.Second
+	if e.Server != nil {
+		timeout = e.Server.Cfg.ReqTimeout()
+	}
 	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(timeout):
+				// took too long, manually close open transports
+				// e.g. watch streams
+				gs.Stop()
+				// concurrent GracefulStop should be interrupted
+				<-ch
+			}
 		}
 	}