Wait Type LCK_M_SIX_ABORT_BLOCKERS

Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. When a client application requests data from the database, the request is placed in a queue and the client application must wait for its turn to access the data. The time that the query spends waiting is called a "wait" and is tracked by SQL Server. This information can be used to identify potential performance bottlenecks and optimize the performance of the database. Wait statistics are commonly used by database administrators to diagnose and troubleshoot performance issues in SQL Server.

In SQL Server, locks are critical for maintaining data consistency and preventing conflicts during concurrent transactions. However, certain lock types can result in waits that impact performance, such as LCK_M_SIX_ABORT_BLOCKERS. Understanding this wait type can help you identify and address locking issues in your database to improve overall performance.

What is LCK_M_SIX_ABORT_BLOCKERS?

The LCK_M_SIX_ABORT_BLOCKERS wait type occurs when a session is waiting to acquire a shared intent exclusive (SIX) lock but is blocked by another session. An SIX lock is often used during operations that read data and intend to update or modify some part of it, requiring both shared and exclusive locks on resources. This wait type specifically indicates that the request to acquire the SIX lock is being delayed due to other blocking transactions that must first be aborted or resolved.

In simpler terms, this wait type means SQL Server is waiting for other transactions to release their locks or complete so that it can acquire the necessary lock to proceed with its task.

Why Does LCK_M_SIX_ABORT_BLOCKERS Happen?

Several factors can contribute to LCK_M_SIX_ABORT_BLOCKERS waits, including:

• Long-running transactions holding locks on the resources required by the waiting session.
• High levels of contention for the same resources, such as tables or indexes.
• Inefficient queries or missing indexes that increase the duration of locks.
• Improper isolation levels that increase the risk of blocking.
• Heavy workloads that create contention between read and write operations.

By addressing these factors, you can reduce the occurrence of these waits and improve concurrency in your SQL Server environment.

How to Monitor LCK_M_SIX_ABORT_BLOCKERS Waits

Monitoring LCK_M_SIX_ABORT_BLOCKERS waits is essential for identifying and resolving locking and blocking issues. The Database Health Monitor is a valuable tool for tracking this wait type. Its Historic Waits Monitoring feature provides insights into when and how often these waits occur, as well as their impact on performance.

By using Database Health Monitor, you can identify patterns of blocking and determine whether they stem from long-running transactions, inefficient queries, or other resource contention issues.

What Can You Do About LCK_M_SIX_ABORT_BLOCKERS Waits?

If you notice frequent or prolonged LCK_M_SIX_ABORT_BLOCKERS waits, consider the following actions:

• Optimize queries to reduce the duration of locks and improve overall performance.
• Review and implement appropriate indexes to reduce contention and speed up queries.
• Analyze blocking chains using tools like Extended Events or Activity Monitor to identify the root cause of blockers.
• Set appropriate transaction isolation levels to balance concurrency and data consistency.
• Break large transactions into smaller ones to minimize the time resources are locked.
• Schedule heavy read or write operations during off-peak hours to reduce contention.

These steps can help alleviate blocking issues and reduce the impact of LCK_M_SIX_ABORT_BLOCKERS waits on your system’s performance.

Why Use Database Health Monitor?

The Database Health Monitor is an essential tool for monitoring SQL Server wait types, including LCK_M_SIX_ABORT_BLOCKERS. Its Historic Waits Monitoring feature provides actionable insights into wait trends, helping you identify and resolve performance bottlenecks related to locking and blocking. With Database Health Monitor, you can ensure your SQL Server environment runs efficiently and handles concurrent workloads effectively.

Start using Database Health Monitor today to optimize your SQL Server’s performance and maintain a high-performing database system!

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Applies to

Related Waits

See Also

• More About LCK_M_SIX_ABORT_BLOCKERS