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

Comience reproduciendo el informe con IoTDB 11.0 en Ubuntu 20.04.1 usando la configuración predeterminada; después, supervise la CPU a lo largo del tiempo y compárela antes y después de stop-server/start-server. El problema se habrá resuelto cuando se identifique la causa del crecimiento sostenido de la CPU y el uso de la CPU deje de aumentar durante una ejecución prolongada con poco tráfico.

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