What to do if oracle deadlock

Oracle Deadlock Handling Guide: Identify Deadlocks: Check for "deadlock detected" errors in log files. View deadlock information: Use the GET_DEADLOCK package or the V$LOCK view to obtain deadlock session and resource information. Analyze deadlock diagram: Generate deadlock diagram to visualize the lock holding and waiting situation and determine the root cause of the deadlock. Rollback deadlock session: Use the KILL SESSION command to roll back the session, but it may cause data loss. Interrupt deadlock cycle: Use the DISCONNECT SESSION command to disconnect the session and release the held lock. Prevent deadlocks: Optimize queries, use optimistic locking, conduct transaction management and regular health checks. Monitoring deadlock:

Oracle Deadlock Handling Guide

In Oracle databases, deadlocks can hinder the normal progress of concurrent operations and lead to degradation of system performance. Deadlock occurs when two or more sessions are waiting for resources to each other. This article provides a detailed guide on how to deal with Oracle deadlocks.

1. Identify deadlocks

The first step to identifying deadlocks is to check the log files of the Oracle database. Deadlock will cause the DBMS to output an error message similar to "deadlock detected".

2. View deadlock information

Once the deadlock is identified, the next step is to view the deadlock information. You can use the DBMS_LOCK.GET_DEADLOCK package or the V$LOCK view to get detailed information about deadlock sessions, held locks, and waiting for resources.

3. Analyze deadlock diagram

The deadlock diagram helps you visualize the details of the deadlock. You can use Oracle Enterprise Manager or third-party tools such as PL/SQL Developer to generate deadlock diagrams. The graph will show the locks held by each session and the locks they are waiting for, which helps determine the source of the deadlock.

4. Roll back the deadlock session

The most direct way to deal with deadlocks is to roll back the deadlock session. You can use KILL SESSION or ALTER SYSTEM KILL SESSION commands. However, be aware that this may lead to data loss.

5. Interrupt deadlock cycle

Another way to deal with deadlocks is to interrupt its loop. You can use the ALTER SYSTEM DISCONNECT SESSION command to disconnect the deadlock session. This allows the session to be placed in an unavailable state, thereby releasing the held lock.

6. Prevent the deadlock

Preventing deadlocks is crucial. Here are some suggestions:

• Optimize queries to reduce the duration of locks
• Read with optimistic locking and unlocked
• Use transaction management to ensure transaction atomicity and consistency
• Regularly perform health checks on the database to detect potential deadlock problems

7. Monitor deadlock

Continuous monitoring of deadlocks is critical to avoid its impact on system performance. You can use Oracle Enterprise Manager or third-party tools to monitor deadlock activity.

The above is the detailed content of What to do if oracle deadlock. For more information, please follow other related articles on the PHP Chinese website!