JVM crash on JMX getSystemCpuLoad when using Sentinel

## Issue Description

Type: *bug report* or *fea
[hs_err_pid6440.log](https://github.com/alibaba/Sentinel/files/9606358/hs_err_pid6440.log)
ture request*

### Describe what happened (or what feature you want)

### Describe what you expected to happen

### How to reproduce it (as minimally and precisely as possible)

1.
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3.

### Tell us your environment

### Anything else we need to know?

Start with the attached hs_err_pid6440.log and the issue title, then investigate the JVM crash occurring during JMX getSystemCpuLoad when using Sentinel. Reproduce the crash in the stated environment, which is not provided in the issue, and identify a verified fix with a regression test or documented reproduction showing that the JVM no longer crashes.

Written by the indexing model from the issue text.