From aa51b46ead53bdbcc1926c606f8214eb99739df5 Mon Sep 17 00:00:00 2001
From: Zhou Kunqin <25057648+time-and-fate@users.noreply.github.com>
Date: Mon, 16 Jan 2023 22:29:49 +0800
Subject: [PATCH] executor: fix concurrent use of `testkit` in tests and add
 nil check (#40627)

close pingcap/tidb#40206
---
 executor/executor_test.go | 6 ++++--
 planner/core/encode.go    | 3 +++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/executor/executor_test.go b/executor/executor_test.go
index a3b2ba0b221ab..6a454bb85a9ea 100644
--- a/executor/executor_test.go
+++ b/executor/executor_test.go
@@ -5556,6 +5556,8 @@ func TestAdmin(t *testing.T) {
 	}))
 	tk := testkit.NewTestKit(t, store)
 	tk.MustExec("use test")
+	tk2 := testkit.NewTestKit(t, store)
+	tk2.MustExec("use test")
 	tk.MustExec("drop table if exists admin_test")
 	tk.MustExec("create table admin_test (c1 int, c2 int, c3 int default 1, index (c1))")
 	tk.MustExec("insert admin_test (c1) values (1),(2),(NULL)")
@@ -5680,7 +5682,7 @@ func TestAdmin(t *testing.T) {
 		// check that the result set has no duplication
 		defer wg.Done()
 		for i := 0; i < 10; i++ {
-			result := tk.MustQuery(`admin show ddl job queries 20`)
+			result := tk2.MustQuery(`admin show ddl job queries 20`)
 			rows := result.Rows()
 			rowIDs := make(map[string]struct{})
 			for _, row := range rows {
@@ -5711,7 +5713,7 @@ func TestAdmin(t *testing.T) {
 		// check that the result set has no duplication
 		defer wg2.Done()
 		for i := 0; i < 10; i++ {
-			result := tk.MustQuery(`admin show ddl job queries limit 3 offset 2`)
+			result := tk2.MustQuery(`admin show ddl job queries limit 3 offset 2`)
 			rows := result.Rows()
 			rowIDs := make(map[string]struct{})
 			for _, row := range rows {
diff --git a/planner/core/encode.go b/planner/core/encode.go
index 14931d4d1ef0a..bf02059dafdda 100644
--- a/planner/core/encode.go
+++ b/planner/core/encode.go
@@ -262,6 +262,9 @@ type planDigester struct {
 
 // NormalizeFlatPlan normalizes a FlatPhysicalPlan and generates plan digest.
 func NormalizeFlatPlan(flat *FlatPhysicalPlan) (normalized string, digest *parser.Digest) {
+	if flat == nil {
+		return "", parser.NewDigest(nil)
+	}
 	selectPlan, selectPlanOffset := flat.Main.GetSelectPlan()
 	if len(selectPlan) == 0 || !selectPlan[0].IsPhysicalPlan {
 		return "", parser.NewDigest(nil)