The ORA-00060 error in Oracle indicates that a deadlock has been detected between two or more sessions. Here are some steps and commands you can take to troubleshoot and resolve this issue:
Identify the Deadlock
Check the Alert Log:
The alert log contains detailed information about the deadlock. You can find it in the Oracle diagnostic directory usually in (ORACLE_HOME/diag/rdbms/<dbname>/<instance>/trace/alert_<instance>.log).
Use the Deadlock Trace File:
Oracle creates a trace file when a deadlock occurs, which provides insights into the sessions involved and the resources they are waiting on. You can find this file in the same trace directory as the alert log.
Query V$SESSION and V$LOCK:
Use the following queries to get more information about the sessions and locks involved in the deadlock:
SELECT * FROM V$SESSION WHERE STATUS = 'ACTIVE';
SELECT * FROM V$LOCK WHERE BLOCK = 1;
Resolve the Deadlock
Kill One of the Sessions:
After identifying the sessions involved in the deadlock, you can terminate one of the sessions to resolve the issue. Use the ALTER SYSTEM command:
ALTER SYSTEM KILL SESSION 'sid,serial#';
Replace sid and serial# with the actual values from the V$SESSION query.
Prevent Future Deadlocks
Optimize Your Application Logic:
Review your application logic to avoid deadlocks by ensuring that transactions acquire locks in a consistent order.
Break large transactions into smaller ones when possible.
Use Lock Timeout Settings:
Set a lock timeout to avoid waiting indefinitely. This can be done using the SET TRANSACTION command:
SET TRANSACTION USE ROLLBACK SEGMENT segment_name;
Or, set the parameter for your session:
ALTER SESSION SET RESOURCE_LIMIT = TRUE;
Monitoring and Troubleshooting
Use Automatic Deadlock Detection:
Enable the _deadlock_detect parameter (if not already enabled) to allow Oracle to automatically detect deadlocks.
Regular Monitoring:
Continuously monitor V$SESSION and V$LOCK views, or set up alerts to notify you when a deadlock occurs.
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