system variables tidb_gc_max_wait_time do not taking effect on all tidb nodes

[vivid392845427]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. connect to tidb-0 and update the system variable value to: set global tidb_gc_max_wait_time = 1200;
2. connect to tidb-1 and query the system variable tidb_gc_max_wait_time value is 1200;
3. Execute tpcc 1000 warehouse, 1024 threads
4. check the tidb log, and confirm that gc and auto analyze are executed on the tidb-1 node, check the execution of gc and auto analyze.

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

gc safepoint is advanced after more than 20 minutes; auto analyze fails after more than 20 minutes

3. What did you see instead (Required)

gc safepoint does not advance for more than 30 minutes, and auto analyze is executed for more than 30 minutes without failure.

4. What is your TiDB version? (Required)

Release Version: v6.1.0-nightly
Edition: Community
Git Commit Hash: dce5064e9e15d0b17c36f73e21fc71bcaa419e90
Git Branch: heads/refs/tags/v6.1.0-nightly
UTC Build Time: 2022-05-25 06:18:14
GoVersion: go1.18.2
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false

[TonsnakeLin]

is is caused by this code:
func (sv *SysVar) SkipSysvarCache() bool {
switch sv.Name {
case TiDBGCEnable, TiDBGCRunInterval, TiDBGCLifetime,
TiDBGCConcurrency, TiDBGCScanLockMode, TiDBGCMaxWaitTime:
TiDBGCConcurrency, TiDBGCScanLockMode:
return true
}
return false
}

If you updated updated tidb_gc_max_wait_time on a tidb instance, but the other tidb can't update the sysvar cache, and if the other tidb executes gc , tidb_gc_max_wait_time doesn't table effect

[TonsnakeLin]

/remove-label may-affects-6.1

[TonsnakeLin]

/label affects-6.1