Constant High CPU Usage

**Describe the bug**
I have a small IOTDB instance running on Ubuntu. Over time the CPU utilisation is very high even though there are a low number of clients and transactions. The CPU usage appears to climb over time. This system has been running for several weeks without a restart. If I run "ps -ef" I can see that it is IOTDB that is using the CPU constantly.

Below is the CPU usage before and after I ran stop-server/start-server. The CPU dropped from > 80% down to < 10%.


**To Reproduce**
Steps to reproduce the behavior:
1. Run IOTDB 11.0 with default settings

**Expected behavior**
The CPU usage should not be so high.

**Screenshots**
See above.

**Desktop (please complete the following information):**
- OS: Ubuntu 20.04.1 LTS
- Browser Not Applicable
- Version 11.0

**Additional context**
None

首先，在 Ubuntu 20.04.1 上使用默认设置通过 IoTDB 11.0 重现报告，然后持续监控 CPU，并比较 stop-server/start-server 前后的情况。当确定 CPU 持续增长的原因，并且在长时间低流量运行期间 CPU 使用率不再上升时，该问题即得到解决。

由索引模型根据 Issue 内容生成。