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

まず、デフォルト設定を使用して Ubuntu 20.04.1 上の IoTDB 11.0 で報告を再現し、その後、時間の経過に伴う CPU を監視して、stop-server/start-server の前後で比較します。持続的な CPU 増加の原因が特定され、低トラフィック状態で長時間実行しても CPU 使用率が上昇しなくなれば、問題は解決です。

索引モデルが issue の本文から書いたものです。