在工程中使用了druid连接池，运行一段时间后系统出现异常：
- Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60009, active 50
- at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
- at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:280)
- ... 64 more
- Caused by: com.alibaba.druid.pool.GetConnectionTimeoutException: wait millis 60000, active 50
- at com.alibaba.druid.pool.DruidDataSource.getConnectionInternal(DruidDataSource.java:1071)
- at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:898)