util: refine expensive query log during bootstrap (#14181)

[sre-bot]

cherry-pick #14181 to release-3.1

---

What problem does this PR solve?

Before this commit:

1. modify the MemQuotaQuery to 32 in config.go
2. compile and try to run the tidb-server binary
3. tidb-server panic and log the following error messge

[2019/12/23 15:13:35.681 +08:00] [ERROR] [adapter.go:122] ["execute sql panic"] [sql="select HIGH_PRIORITY Host,User,Password,Create_priv, Super_priv, Execute_priv, Create_view_priv, Create_role_priv, Event_priv, Update_priv, Show_db_priv, Create_user_priv, Trigger_priv, Grant_priv, References_priv, Lock_tables_priv, Drop_role_priv, Select_priv, Insert_priv, Drop_priv, Process_priv, Alter_priv, Index_priv, Show_view_priv, Alter_routine_priv, Shutdown_priv, Delete_priv, Create_tmp_table_priv, Create_routine_priv,account_locked from mysql.user;"] [stack="github.com/pingcap/tidb/executor.(*recordSet).Next.func1\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/adapter.go:122\nruntime.gopanic\n\t/Users/xuhuaiyu/.gvm/gos/go1.13/src/runtime/panic.go:679\nruntime.panicmem\n\t/Users/xuhuaiyu/.gvm/gos/go1.13/src/runtime/panic.go:199\nruntime.sigpanic\n\t/Users/xuhuaiyu/.gvm/gos/go1.13/src/runtime/signal_unix.go:394\ngithub.com/pingcap/tidb/util/expensivequery.(*Handle).LogOnQueryExceedMemQuota\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/util/expensivequery/expensivequery.go:85\ngithub.com/pingcap/tidb/util/memory.(*LogOnExceed).Action\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/util/memory/action.go:64\ngithub.com/pingcap/tidb/util/memory.(*Tracker).Consume\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/util/memory/tracker.go:194\ngithub.com/pingcap/tidb/executor.(*ProjectionExec).prepare\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/projection.go:248\ngithub.com/pingcap/tidb/executor.(*ProjectionExec).parallelExecute\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/projection.go:199\ngithub.com/pingcap/tidb/executor.(*ProjectionExec).Next\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/projection.go:172\ngithub.com/pingcap/tidb/executor.Next\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/executor.go:212\ngithub.com/pingcap/tidb/executor.(*recordSet).Next\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/executor/adapter.go:125\ngithub.com/pingcap/tidb/privilege/privileges.(*MySQLPrivilege).loadTable\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/privilege/privileges/cache.go:522\ngithub.com/pingcap/tidb/privilege/privileges.(*MySQLPrivilege).LoadUserTable\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/privilege/privileges/cache.go:354\ngithub.com/pingcap/tidb/privilege/privileges.(*MySQLPrivilege).LoadAll\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/privilege/privileges/cache.go:269\ngithub.com/pingcap/tidb/privilege/privileges.(*Handle).Update\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/privilege/privileges/cache.go:1250\ngithub.com/pingcap/tidb/domain.(*Domain).LoadPrivilegeLoop\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/domain/domain.go:780\ngithub.com/pingcap/tidb/session.BootstrapSession\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/session/session.go:1616\nmain.createStoreAndDomain\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/tidb-server/main.go:247\nmain.main\n\t/Users/xuhuaiyu/Development/GOPATH/src/github.com/pingcap/tidb/tidb-server/main.go:185\nruntime.main\n\t/Users/xuhuaiyu/.gvm/gos/go1.13/src/runtime/proc.go:203"]
[2019/12/23 15:13:35.682 +08:00] [WARN] [cache.go:271] ["load mysql.user fail"] [error="runtime error: invalid memory address or nil pointer dereference"]
2019/12/23 15:13:35.682 terror.go:344: [fatal] [privilege:8049]mysql.user

What is changed and how it works?

Check whether expensiveQueryHandler.sm is nil before using it.

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. modify the MemQuotaQuery to 32 in config.go
2. compile and try to run the tidb-server binary
3. everything works fine

[2019/12/23 16:22:44.091 +08:00] [INFO] [domain.go:369] ["full load and reset schema validator"]
[2019/12/23 16:22:44.095 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.097 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.099 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.100 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.101 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.102 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.102 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.103 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.103 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.104 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.104 +08:00] [INFO] [expensivequery.go:91] ["expensive_query during bootstrap phase"] [conn_id=0]
[2019/12/23 16:22:44.104 +08:00] [WARN] [server.go:270] ["secure connection is not enabled"]
[2019/12/23 16:22:44.104 +08:00] [INFO] [server.go:225] ["server is running MySQL protocol"] [addr=0.0.0.0:4000]
[2019/12/23 16:22:44.107 +08:00] [INFO] [domain.go:987] ["init stats info time"] ["take time"=4.011721ms]
[2019/12/23 16:22:44.108 +08:00] [INFO] [http_status.go:266] ["for status and metrics report"] ["listening on addr"=0.0.0.0:10080]

Code changes

• Has exported function/method change

Side effects

N/A

Related changes

• Need to cherry-pick to the release branch

Release note

N/A

[sre-bot]

/run-all-tests

[XuHuaiyu]

/run-all-tests

[SunRunAway]

LGTM

[qw4990]

LGTM

[XuHuaiyu]

/run-all-tests

[zz-jason]

LGTM