oracle 11g bug：修改普通用户密码挂住，所有客户端均连接不上，生产中断分析
环境：
Oracle 11.2.0.2 RAC for IBM AIX 6.1 2节点
一条简单的修改用户密码SQL语句 ：
alter user ** identified by ***;
竟然会挂住在那，此时所有的客户端（.net架构短连接）均无法连接，也是连接出不来，也不报错。
此时做了个10046，生成了个跟踪文件如 附件。
后重启了2个节点数据库后，用了不到5分钟，又出现所有客户端无法连接数据库。
FYI:
相关bUG
Description
In 11g there is an intentional delay between allowing failed logon
attempts to retry. For some specific application types this can cause
a problem as the row cache entry is locked for the duration of the
delay . This can lead to excessive row cache lock waits for DC_USERS
for specific users / schemas .
This "fix" allows the logon delay to be disabled in 11.2.0.1 onwards
by setting event 28401 in the init.ora.
eg:
event="28401 trace name context forever, level 1" # disable logon delay.
This "event" will disable the logon sleep delay system-wide,
ie. it will affect all user accounts, system-wide, and so should be used
with extreme caution.
Example scenario:
A mix of correct and incorrect logon attempts occur for user X
On each successive failed login attempt the failed logon count
is incremented for user X.
Without this fix (without the event set):
After 3 successive failures a sleep delay is introduced starting
at 3 seconds and extending to 10 seconds max. During each delay
the user X row cache lock is held in exclusive mode preventing
any concurrent logon attempt as user X (and preventing any
other operation which would need the row cache lock for user X).
With the fix (with the event set):
There is no sleep delay.
In either scenario the configured logon profile rules are still
applied (eg: The profile option FAILED_LOGIN_ATTEMPTS is still
honoured and so if the account becomes locked due to exceeeding
this FAILED_LOGIN_ATTEMPTS then further attempts to
log in will then correctly fail immediately with no delay).
Note:
One off fixes for this issue for 11.1.0.7 do not need an event set -
interim patches for 11.1 disable the delay unconditionally.
Work Around:
Ensure the correct password is used - especially for connection
intensive logons
Getting a Fix
Use one of the "Fixed" versions listed above
(for Patch Sets / bundles use the latest version available as
contents are cumulative - the "Fixed" version listed above is
the first version where the fix is included)
or
You can check for existing interim patches here: Patch:7715339
总结：
alter system set event="10949 TRACE NAME CONTEXT FOREVER:28401 trace name context forever, level 1" scope=spfile;
这2个event 仍是在11g 中推荐设置的
后经过验证确实是属于11g 错误密码验证延时功能所导致
