DATA RACE in the domain.(*Domain).SetDDL()

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

 WARNING: DATA RACE
Write at 0x00c005ab0a38 by goroutine 81:
  github.com/pingcap/tidb/domain.(*Domain).SetDDL()
      /go/tidb/domain/domain.go:381 +0x2a6
  github.com/pingcap/tidb/ddl_test.TestAnonymousIndex()
      /go/tidb/ddl/index_modify_test.go:1069 +0x299
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1486 +0x47
Previous read at 0x00c005ab0a38 by goroutine 180:
  github.com/pingcap/tidb/domain.(*Domain).loadSchemaInLoop()
      /go/tidb/domain/domain.go:611 +0x10c
  github.com/pingcap/tidb/domain.(*Domain).Init.func4()
      /go/tidb/domain/domain.go:887 +0x64
Goroutine 81 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:1486 +0x724
  testing.runTests.func1()
      /usr/local/go/src/testing/testing.go:1839 +0x99
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.runTests()
      /usr/local/go/src/testing/testing.go:1837 +0x7e4
  testing.(*M).Run()
      /usr/local/go/src/testing/testing.go:1719 +0xa71
  go.uber.org/goleak.VerifyTestMain()
      /home/prow/go/pkg/mod/go.uber.org/[email protected]/testmain.go:53 +0x59
  github.com/pingcap/tidb/ddl_test.TestMain()
      /go/tidb/ddl/main_test.go:68 +0x5f9
  main.main()
      _testmain.go:1345 +0x3f7
Goroutine 180 (running) created at:
  github.com/pingcap/tidb/domain.(*Domain).Init()
      /go/tidb/domain/domain.go:887 +0x1294
  github.com/pingcap/tidb/session.(*domainMap).Get.func1()
      /go/tidb/session/tidb.go:85 +0x664
  github.com/pingcap/tidb/util.RunWithRetry()
      /go/tidb/util/misc.go:69 +0x93
  github.com/pingcap/tidb/session.(*domainMap).Get()
      /go/tidb/session/tidb.go:73 +0x319
  github.com/pingcap/tidb/session.createSessionWithOpt()
      /go/tidb/session/session.go:2821 +0x75
  github.com/pingcap/tidb/session.createSession()
      /go/tidb/session/session.go:2817 +0x84
  github.com/pingcap/tidb/session.createSessions()
      /go/tidb/session/session.go:2806 +0x6e
  github.com/pingcap/tidb/session.BootstrapSession()
      /go/tidb/session/session.go:2685 +0x317
  github.com/pingcap/tidb/testkit.bootstrap()
      /go/tidb/testkit/mockstore.go:71 +0x8c
  github.com/pingcap/tidb/testkit.CreateMockStoreAndDomainWithSchemaLease()
      /go/tidb/testkit/mockstore.go:94 +0xd8
  github.com/pingcap/tidb/ddl_test.TestAnonymousIndex()
      /go/tidb/ddl/index_modify_test.go:1065 +0x5d
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1486 +0x47 

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)