几日前生产环境遇到一问题，经查证，问题解决，大体过程如下：

一：问题根源：系统参数小于实际需要参数大小

二：基本环境：redhat6.2 +oracle11g rac

三：分析过程：

现场反馈程序无法正常连接数据库，但登录系统后，监听正常。

1.alert告警日志无报错信息

2.监听日志信息错误信息如下：

(CONNECT_DATA=(SID=uflowcb1)(CID=(PROGRAM=)(HOST=__jdbc__)(USER=))) * (ADDRESS=(PROTOCOL=tcp)(HOST=**)(PORT=42961)) * establish * udc * 12518

TNS-12518: TNS:listener could not hand off client connection

TNS-12536: TNS:operation would block

TNS-12560: TNS:protocol adapter error

TNS-00506: Operation would block

Linux Error: 11: Resource temporarily unavailable

3.错误核对官方文档显示：

ORA-12536: TNS:operation would block Cause: An internal operation did not commence because to do so would block the current process and the user has requested that oper