Panic caused by tidb-dashboard profiling

[shhdgit]

Bug Report

What did you do?

Open TiDB Dashboard, select Advanced Debugging -> Profiling Instance, select tikv instance and click Start Profiling. Then return to Profiling Instance page and start another profile again in 10s, PD will panic. Or select 2 pd instances, PD will also panic.

What did you expect to see?

PD won't panic.

What did you see instead?

PD panic and the cluster is unavailable.

What version of PD are you using (pd-server -V)?

Release Version: v5.2.2-2-g42fbbd3
Edition: Community
Git Commit Hash: 42fbbd3c08abe89e485d4c00ce68e37e9b053513
Git Branch: release-5.2
UTC Build Time:  2021-10-29 06:23:35