Instance does not open spinning with 100% CPU utilization

(Doc ID 1554569.1)

Last updated on OCTOBER 10, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 11.1.0.7 to 11.2.0.4 [Release 11.1 to 11.2]
Information in this document applies to any platform.
***Checked for relevance on 01-Sep-2017***

Symptoms

+ Oracle Database 11.1.0.7 (Standalone) got hung and no more connections were feasible including SYSDBA.
+ Customer took the decision to kill SMON at the operating system level.
+ Since then, the instance can be mounted but never opened.
+ When startup is issued, a new Oracle process is forked at the OS with 100% CPU usage.
+ The V$INSTANCE.STATUS shows OPEN, and the V$DATABASE.OPEN_MODE shows READ WRITE.
+ However, the "alter database open" is never reported as completed in the alert log file.
+ Also, the DBA_* and V$* views are accessible. However, no connections can be done to the application schemas.
+ Trying to "startup upgrade" hangs also.

 

Changes

 Background SMON was killed explicitly at the operating system level when instance was hung.

Cause

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