From b390a2a0b9034f2ee71f786fbfc028fe14655254 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Wed, 16 Dec 2020 14:33:05 -0800
Subject: [PATCH] fix: reuser timers in erasure set hotpaths (#11106)

reuser timers in

 - connectDisks() monitoring
 - healMRFRoutine() channel timeouts
---
 cmd/erasure-sets.go     | 26 +++++++++++++++++++++++---
 cmd/metacache-bucket.go |  3 ++-
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/cmd/erasure-sets.go b/cmd/erasure-sets.go
index 3db81f756..c2d7808ee 100644
--- a/cmd/erasure-sets.go
+++ b/cmd/erasure-sets.go
@@ -245,10 +245,13 @@ func (s *erasureSets) connectDisks() {
 			s.endpointStrings[setIndex*s.setDriveCount+diskIndex] = disk.String()
 			s.erasureDisksMu.Unlock()
 			go func(setIndex int) {
+				idler := time.NewTimer(100 * time.Millisecond)
+				defer idler.Stop()
+
 				// Send a new disk connect event with a timeout
 				select {
 				case s.disksConnectEvent <- diskConnectInfo{setIndex: setIndex}:
-				case <-time.After(100 * time.Millisecond):
+				case <-idler.C:
 				}
 			}(setIndex)
 		}(endpoint)
@@ -267,13 +270,22 @@ func (s *erasureSets) monitorAndConnectEndpoints(ctx context.Context, monitorInt
 	// Pre-emptively connect the disks if possible.
 	s.connectDisks()
 
+	monitor := time.NewTimer(monitorInterval)
+	defer monitor.Stop()
+
 	for {
 		select {
 		case <-ctx.Done():
 			return
-		case <-time.After(monitorInterval):
+		case <-monitor.C:
 			s.connectDisks()
 		}
+
+		if !monitor.Stop() {
+			<-monitor.C
+		}
+
+		monitor.Reset(monitorInterval)
 	}
 }
 
@@ -1363,6 +1375,9 @@ func (s *erasureSets) healMRFRoutine() {
 	// Wait until background heal state is initialized
 	bgSeq := mustGetHealSequence(GlobalContext)
 
+	idler := time.NewTimer(100 * time.Millisecond)
+	defer idler.Stop()
+
 	for e := range s.disksConnectEvent {
 		// Get the list of objects related the er.set
 		// to which the connected disk belongs.
@@ -1380,8 +1395,13 @@ func (s *erasureSets) healMRFRoutine() {
 			// Send an object to be healed with a timeout
 			select {
 			case bgSeq.sourceCh <- u:
-			case <-time.After(100 * time.Millisecond):
+			case <-idler.C:
+			}
+
+			if !idler.Stop() {
+				<-idler.C
 			}
+			idler.Reset(100 * time.Millisecond)
 
 			s.mrfMU.Lock()
 			delete(s.mrfOperations, u)
diff --git a/cmd/metacache-bucket.go b/cmd/metacache-bucket.go
index e151de6ab..a68b3a244 100644
--- a/cmd/metacache-bucket.go
+++ b/cmd/metacache-bucket.go
@@ -87,7 +87,8 @@ func loadBucketMetaCache(ctx context.Context, bucket string) (*bucketMetacache,
 		select {
 		case <-ctx.Done():
 			return nil, ctx.Err()
-		case <-time.After(250 * time.Millisecond):
+		default:
+			time.Sleep(250 * time.Millisecond)
 		}
 		objAPI = newObjectLayerFn()
 		if objAPI == nil {