Oracle11g、12c大量错误登陆尝试带来的数据库异常

APPLIES TO:

创新互联公司专注为客户提供全方位的互联网综合服务，包含不限于成都网站制作、成都做网站、外贸营销网站建设、富民网络推广、微信小程序、富民网络营销、富民企业策划、富民品牌公关、搜索引擎seo、人物专访、企业宣传片、企业代运营等，从售前售中售后，我们都将竭诚为您服务，您的肯定，是我们最大的嘉奖；创新互联公司为所有大学生创业者提供富民建站搭建服务，24小时服务热线：18982081108，官方网址：www.cdcxhl.com

Oracle Database - Enterprise Edition - Version 10.2.0.5 and later
Information in this document applies to any platform.

CAUSE

A hang is possible in earlier versions of RDBMS as a result of an unpublished bug fixed in the following versions:

    12.1.0.1 (Base Release)
    11.2.0.2 (Server Patch Set)
    11.1.0.7 Patch 42 on Windows Platforms

Document 9776608.8 Bug 9776608 - Hang from concurrent login to same account with a wrong password

Even with this fix, numerous failed logins attempts can cause row cache lock waits and/or library cache lock waits. 

This was reported in:

Bug 11742803 LOTS OF 'LIBRARY CACHE LOCK' DURING USER LOGON AUTHENTICATION
This was closed as not a bug because there is an intentional wait when a login fails.

SOLUTION

In Oracle 11g Release 11.1.0.7,  the wait is disabled unconditionally
In Oracle 11g Release 2 and higher, in order to disable the wait between login failures the event 28401 needs to be explicitly enabled:
The event can be set as follows:

alter system set event ="28401 TRACE NAME CONTEXT FOREVER, LEVEL 1" scope=spfile;

To unset the event, set as follows:
SQL> Alter system set event= '28401 trace name context off' scope=spfile ;

小结：
关于大量的并发的错误密码连接数据库可能会导致数据库hang、或者引起性能问题，对数据库的影响非常大，近期就遇到过这样的一个案例。当然Oracle本身这个特性是非常好的，但是在当下确实会遇到一些问题，大家可以使用event 28401禁用这个特性。但是最好是要从管理上解决掉这样的问题，从安全层面做好管控。

当前文章：Oracle11g、12c大量错误登陆尝试带来的数据库异常
分享网址：http://bjjierui.cn/article/pcogjo.html