druid 连接池出现 GetConnectionTimeoutException 异常

**1、bug描述** mycat 使用了一段时间（大约一个月）后，druid 会出现创建新连接超时的异常 nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60000, active 0, maxActive 100, creating 1, createElapseMillis 6995022