iotdb process pretends to be dead and cannot query and write

error reporting during query execution:
may not ready now, please wait and retry later

log_error.log:
2021-12-17 11:50:37,997 [pool-4-IoTDB-Compaction-5] ERROR o.a.i.d.e.c.l.LevelCompactionTsFileManagement:697 - Error occurred in Compaction Merge thread
java.lang.NullPointerException: null
2021-12-17 11:50:48,433 [MergeThread-0] ERROR o.a.i.d.e.m.t.MergeTask:111 - Runtime exception in merge root.benchmark.-1639713043742
java.lang.ClassCastException: null

从 LevelCompactionTsFileManagement 和 MergeTask 报告的压缩错误入手，然后调查它们与查询和写入失败之间的关系。如果可能，重现报告的状态；当 IoTDB 进程在不出现这些压缩异常的情况下仍可用于查询和写入时，即表示完成。

由索引模型根据 Issue 内容生成。