合 【MOS】High 'library cache lock' Wait Time Due to Invalid Login Attempts (Doc ID 1309738.1)

APPLIES TO:

Oracle Database - Enterprise Edition - Version 10.2.0.5 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.

SYMPTOMS

• 'Library cache lock' or 'row cache lock' can be observed when concurrent users login with wrong password to the database.

• The 'row cache lock' is seen in 10.2 and 11.1 while the 'library cache lock' is seen in 11.2.

• ASH Report displays

  • High Percentage of execution time attributed to Connection Management:

  • High percentage of calls of type OAUTH

  

• Stack contains one of the following functions:

  kziavua
  kziaia
  kziasfc

• Checking the

  exclusive

  holder from DBA_DDL_LOCKS, a session may be seen holding a lock type (kglhdnsp) 79 on object (kglnaobj) 5:

  SQL> select * from dba_ddl_locks where mode_held='Exclusive';

  SESSION_ID OWNER NAME TYPE MODE_HELD MODE_REQU

  ---------- --------- ---------- ---------- --------- ---------

  612 5 79 Exclusive None

• If AUDIT_TRAIL is enabled, login failures can be checked by running SQLs similar to the following:

  Checks for entries in the last 7 days in DBA_AUDIT_TRAIL with error ORA-1017 invalid username/password; logon denied

  select username, os_username, userhost, client_id, trunc(timestamp), count(*) fa**iled_logins from dba_audit_trail where returncode = 1017 and timestamp > sysdate - 7 group by username, os_username, userhost, client_id, trunc(timestamp);**

• Checks for entries in the last 7 days in DBA_AUDIT_SESSION where an error was returned

  select username, os_username, userhost, timestamp, returncode from sys.dba_audit_session where returncode != 0 and timestamp > sysdate - 7;

CHANGES

Many users with wrong password try to login to the database simultaneously

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A hang is possible in earlier versions of RDBMS as a result of an unpublished bug fixed in the following versions: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

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