From 690a0b6f009ee48769ce2b56c6ba7bad9c5b9433 Mon Sep 17 00:00:00 2001
From: fanmin shi <fanmin.shi@coreos.com>
Date: Fri, 16 Sep 2016 16:57:55 -0700
Subject: [PATCH] etcdserver: parallelize expired leases process

When 1000 leases expired at the same time, etcd takes more than 5 seconds to clean them. This means that even after the leases have expired, keys associated with leases are still accessible. I increase the deletion throughput by parallelizing leases deletion process.
---
 etcdserver/server.go | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/etcdserver/server.go b/etcdserver/server.go
index 903e55163..3bc8d81d6 100644
--- a/etcdserver/server.go
+++ b/etcdserver/server.go
@@ -81,6 +81,9 @@ const (
 	maxInFlightMsgSnap = 16
 
 	releaseDelayAfterSnapshot = 30 * time.Second
+
+	// maxPendingRevokes is the maximum number of outstanding expired lease revocations.
+	maxPendingRevokes = 16
 )
 
 var (
@@ -619,8 +622,19 @@ func (s *EtcdServer) run() {
 			sched.Schedule(f)
 		case leases := <-expiredLeaseC:
 			s.goAttach(func() {
-				for _, l := range leases {
-					s.LeaseRevoke(context.TODO(), &pb.LeaseRevokeRequest{ID: int64(l.ID)})
+				// Increases throughput of expired leases deletion process through parallelization
+				c := make(chan struct{}, maxPendingRevokes)
+				for _, lease := range leases {
+					select {
+					case c <- struct{}{}:
+					case <-s.stopping:
+						return
+					}
+					lid := lease.ID
+					s.goAttach(func() {
+						s.LeaseRevoke(context.TODO(), &pb.LeaseRevokeRequest{ID: int64(lid)})
+						<-c
+					})
 				}
 			})
 		case err := <-s.errorc: