From 74ac033db10b6c82b4d0fdce2d3b0ef57ac31325 Mon Sep 17 00:00:00 2001
From: Hangjie Mo <mohangjie1995@gmail.com>
Date: Thu, 3 Nov 2022 21:44:01 +0800
Subject: [PATCH] server: fix deadlock when call `killNonFlashbackConn`
 (#38872)

close pingcap/tidb#38862
---
 DEPS.bzl         |  4 ++--
 go.mod           |  2 +-
 go.sum           |  4 ++--
 server/server.go | 10 +++++++---
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/DEPS.bzl b/DEPS.bzl
index e9ccd20301ea6..6165078e5d9ff 100644
--- a/DEPS.bzl
+++ b/DEPS.bzl
@@ -3469,8 +3469,8 @@ def go_deps():
         name = "com_github_tikv_client_go_v2",
         build_file_proto_mode = "disable_global",
         importpath = "github.com/tikv/client-go/v2",
-        sum = "h1:NvQHWk0GeXSLEBbmGMPnDMc0to0a3ogzgIRbTKw8MHI=",
-        version = "v2.0.1-0.20221031063202-30e803b7082c",
+        sum = "h1:x5L32xr5KE2C0UhlKfrsDTWQ/8fpFYQLq5xn+ph0sQ0=",
+        version = "v2.0.3-0.20221103084528-ec1202a9d26f",
     )
     go_repository(
         name = "com_github_tikv_pd_client",
diff --git a/go.mod b/go.mod
index 576f3d74d0c1a..41fb7aa9d4a27 100644
--- a/go.mod
+++ b/go.mod
@@ -85,7 +85,7 @@ require (
 	github.com/stretchr/testify v1.8.0
 	github.com/tdakkota/asciicheck v0.1.1
 	github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2
-	github.com/tikv/client-go/v2 v2.0.1-0.20221031063202-30e803b7082c
+	github.com/tikv/client-go/v2 v2.0.3-0.20221103084528-ec1202a9d26f
 	github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07
 	github.com/timakin/bodyclose v0.0.0-20210704033933-f49887972144
 	github.com/twmb/murmur3 v1.1.3
diff --git a/go.sum b/go.sum
index 65a2845209c37..0b15dbe804918 100644
--- a/go.sum
+++ b/go.sum
@@ -909,8 +909,8 @@ github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3 h1:f+jULpR
 github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3/go.mod h1:ON8b8w4BN/kE1EOhwT0o+d62W65a6aPw1nouo9LMgyY=
 github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2 h1:mbAskLJ0oJfDRtkanvQPiooDH8HvJ2FBh+iKT/OmiQQ=
 github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2/go.mod h1:2PfKggNGDuadAa0LElHrByyrz4JPZ9fFx6Gs7nx7ZZU=
-github.com/tikv/client-go/v2 v2.0.1-0.20221031063202-30e803b7082c h1:NvQHWk0GeXSLEBbmGMPnDMc0to0a3ogzgIRbTKw8MHI=
-github.com/tikv/client-go/v2 v2.0.1-0.20221031063202-30e803b7082c/go.mod h1:X9s4ct/MLk1sFqe5mU79KClKegLFDTa/FCx3hzexGtk=
+github.com/tikv/client-go/v2 v2.0.3-0.20221103084528-ec1202a9d26f h1:x5L32xr5KE2C0UhlKfrsDTWQ/8fpFYQLq5xn+ph0sQ0=
+github.com/tikv/client-go/v2 v2.0.3-0.20221103084528-ec1202a9d26f/go.mod h1:X9s4ct/MLk1sFqe5mU79KClKegLFDTa/FCx3hzexGtk=
 github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07 h1:ckPpxKcl75mO2N6a4cJXiZH43hvcHPpqc9dh1TmH1nc=
 github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07/go.mod h1:CipBxPfxPUME+BImx9MUYXCnAVLS3VJUr3mnSJwh40A=
 github.com/timakin/bodyclose v0.0.0-20210704033933-f49887972144 h1:kl4KhGNsJIbDHS9/4U9yQo1UcPQM0kOMJHn29EoH/Ro=
diff --git a/server/server.go b/server/server.go
index 408594bb696b8..eb1f3d6ec951d 100644
--- a/server/server.go
+++ b/server/server.go
@@ -949,20 +949,24 @@ func (s *Server) CheckOldRunningTxn(job2ver map[int64]int64, job2ids map[int64]s
 // KillNonFlashbackClusterConn implements SessionManager interface.
 func (s *Server) KillNonFlashbackClusterConn() {
 	s.rwlock.RLock()
-	defer s.rwlock.RUnlock()
+	connIDs := make([]uint64, 0, len(s.clients))
 	for _, client := range s.clients {
 		if client.ctx.Session != nil {
 			processInfo := client.ctx.Session.ShowProcess()
 			ddl, ok := processInfo.StmtCtx.GetPlan().(*core.DDL)
 			if !ok {
-				s.Kill(client.connectionID, false)
+				connIDs = append(connIDs, client.connectionID)
 				continue
 			}
 			_, ok = ddl.Statement.(*ast.FlashBackToTimestampStmt)
 			if !ok {
-				s.Kill(client.connectionID, false)
+				connIDs = append(connIDs, client.connectionID)
 				continue
 			}
 		}
 	}
+	s.rwlock.RUnlock()
+	for _, id := range connIDs {
+		s.Kill(id, false)
+	}
 }