应该是对应的 memTracker 哪里出了问题，
有可能是这个 issue → Should clean the memory usage of MemTracker when a hashJoin query ends · Issue #34571 · pingcap/tidb · GitHub
修复 pr → executor: fix processlist's Mem is not zero when HashJoin finished by wshwsh12 · Pull Request #34569 · pingcap/tidb · GitHub