From 5443e876cb2bde545557466a0906be9a6556ab3f Mon Sep 17 00:00:00 2001
From: Jacky Wang <jackyw.se@gmail.com>
Date: Thu, 6 Jan 2022 16:43:07 -0800
Subject: [PATCH 1/3] fix an data race cause by early unlock

---
 api/service/legacysync/syncing.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/api/service/legacysync/syncing.go b/api/service/legacysync/syncing.go
index 447f29999f..5a9b9a0a82 100644
--- a/api/service/legacysync/syncing.go
+++ b/api/service/legacysync/syncing.go
@@ -1195,8 +1195,9 @@ func getSyncStatusExpiration(role nodeconfig.Role) time.Duration {
 func (status *syncStatus) Get(fallback func() SyncCheckResult) SyncCheckResult {
 	status.lock.RLock()
 	if !status.expired() {
+		result := status.lastResult
 		status.lock.RUnlock()
-		return status.lastResult
+		return result
 	}
 	status.lock.RUnlock()
 

From a433d277f948f87e6823537001bfd73eac748d90 Mon Sep 17 00:00:00 2001
From: Jacky Wang <jackyw.se@gmail.com>
Date: Thu, 6 Jan 2022 17:46:02 -0800
Subject: [PATCH 2/3] add a concurrency test for syncing cache

---
 api/service/legacysync/syncing_test.go | 45 ++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/api/service/legacysync/syncing_test.go b/api/service/legacysync/syncing_test.go
index 3a17c82bad..1d1e19a292 100644
--- a/api/service/legacysync/syncing_test.go
+++ b/api/service/legacysync/syncing_test.go
@@ -6,7 +6,10 @@ import (
 	"math/big"
 	"reflect"
 	"strings"
+	"sync"
+	"sync/atomic"
 	"testing"
+	"time"
 
 	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
 
@@ -250,3 +253,45 @@ func makeTestBlock(bn uint64, parentHash common.Hash) *types.Block {
 	block := types.NewBlockWithHeader(testHeader)
 	return block
 }
+
+func TestSyncStatus_Get_Concurrency(t *testing.T) {
+	ss := newSyncStatus(nodeconfig.Validator)
+	ss.expiration = 2 * time.Second
+	var (
+		total   int32
+		updated int32
+		wg      sync.WaitGroup
+		stop    = make(chan struct{})
+	)
+
+	fb := func() SyncCheckResult {
+		time.Sleep(1 * time.Second)
+		atomic.AddInt32(&updated, 1)
+		return SyncCheckResult{IsInSync: true}
+	}
+	for i := 0; i != 20; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+
+			t := time.NewTicker(20 * time.Millisecond)
+			defer t.Stop()
+			for {
+				select {
+				case <-stop:
+					return
+				case <-t.C:
+					atomic.AddInt32(&total, 1)
+					ss.Get(fb)
+				}
+			}
+		}()
+	}
+
+	time.Sleep(10 * time.Second)
+	close(stop)
+	wg.Wait()
+
+	fmt.Printf("updated %v times\n", updated)
+	fmt.Printf("total %v times\n", total)
+}

From 1a505a17d7b334bbfbe187b8c3a7bdbd728aa66c Mon Sep 17 00:00:00 2001
From: Jacky Wang <jackyw.se@gmail.com>
Date: Thu, 6 Jan 2022 17:57:31 -0800
Subject: [PATCH 3/3] skip the concurrent test for sync status

---
 api/service/legacysync/syncing_test.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/api/service/legacysync/syncing_test.go b/api/service/legacysync/syncing_test.go
index 1d1e19a292..63f2f5705c 100644
--- a/api/service/legacysync/syncing_test.go
+++ b/api/service/legacysync/syncing_test.go
@@ -255,6 +255,8 @@ func makeTestBlock(bn uint64, parentHash common.Hash) *types.Block {
 }
 
 func TestSyncStatus_Get_Concurrency(t *testing.T) {
+	t.Skip()
+
 	ss := newSyncStatus(nodeconfig.Validator)
 	ss.expiration = 2 * time.Second
 	var (