[BUG]在使用JSON.toJSONString序列化对象时出现OutOfMemoryError: Metaspace

### 问题描述
在生产环境打印较多日志时使用JSON.toJSONString序列化对象时会出现OutOfMemoryError: Metaspace

### 环境信息
*请填写以下信息：*

- OS信息： [e.g.：CentOS 8.4.2105 4Core 3.10GHz 16 GB]
- JDK信息： [e.g.：Openjdk 1.8.0_312]
- 版本信息：[e.g.：Fastjson2 2.0.38]

### 重现步骤
调用JSON.toJSONString方法

#### 附加信息

Start at the JSON.toJSONString entry point and reproduce the reported OutOfMemoryError: Metaspace during heavy logging and object serialization. The issue names no source file or test and omits the JDK, Fastjson2 version, and concrete object, so collect those details first; done means a verified reproduction and a confirmed resolution without Metaspace exhaustion.

Written by the indexing model from the issue text.