Wait Type LCK_M_SIU_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.

SQL Server uses wait types to help identify where processes may encounter delays. The LCK_M_SIU_ABORT_BLOCKERS wait type occurs when a process is attempting to acquire a Shared with Intent Update (SIU) lock but is unable to do so because of blockers. This wait type signals that SQL Server is configured to abort blocking transactions to allow the SIU lock to proceed. Let’s explore what this means, when it happens, and how you can address it.

What Is the LCK_M_SIU_ABORT_BLOCKERS Wait Type?

The LCK_M_SIU_ABORT_BLOCKERS wait type appears when a process is waiting for a Shared with Intent Update (SIU) lock, which allows a transaction to read data while preparing for potential updates. If another transaction is blocking this lock, and SQL Server is configured to abort the blockers, this wait type is logged.

Such configurations are often used to reduce lock contention and maintain transaction flow in high-concurrency environments.

When Does LCK_M_SIU_ABORT_BLOCKERS Appear?

This wait type commonly occurs in the following scenarios:

• Concurrent Read and Update Operations – When multiple transactions are attempting to read and update the same data.
• Blocked Locks – When an existing lock prevents a transaction from acquiring the SIU lock.
• High Contention – In environments with frequent concurrent access to the same data.
• Abort Configuration – When SQL Server is configured to terminate blocking transactions to allow other operations to proceed.

Why LCK_M_SIU_ABORT_BLOCKERS Waits Matter

While this wait type can be expected in certain environments, prolonged or frequent waits may indicate performance issues. Common causes include:

• Long-Running Transactions – Transactions holding locks for extended periods can block SIU locks and delay other processes.
• High Contention – Multiple concurrent processes attempting to access the same data can lead to increased locking conflicts.
• Large Batch Operations – Batch processes that update or read large datasets may hold locks for longer, increasing contention.
• Insufficient Indexing – Poor indexing strategies can result in broader locking and more conflicts.

How to Address LCK_M_SIU_ABORT_BLOCKERS Waits

If this wait type is affecting performance, consider the following strategies to minimize its impact:

• Optimize Queries – Ensure queries are efficient and minimize the scope of data being locked.
• Monitor Blocking Transactions – Identify and resolve long-running transactions that hold locks unnecessarily.
• Improve Indexing – Use appropriate indexing strategies to reduce lock contention and speed up data access.
• Break Down Batch Operations – Divide large batch processes into smaller transactions to reduce lock duration.
• Schedule Operations – Perform high-contention operations during periods of lower activity to minimize their impact.

Monitoring LCK_M_SIU_ABORT_BLOCKERS Waits

To track this wait type and understand its impact on your SQL Server environment, you can use the Historic Waits Monitoring feature in Database Health Monitor. This tool helps you analyze wait statistics over time, identify patterns, and pinpoint sources of contention. Regular monitoring enables you to take proactive steps to optimize performance.

Stedman Solutions specializes in SQL Server performance tuning and optimization. Whether you need help addressing LCK_M_SIU_ABORT_BLOCKERS waits or other performance challenges, our Database Health Monitor tool provides powerful insights, and our managed services ensure your SQL Server runs efficiently. Contact us today to learn how we can help improve your SQL Server performance.

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Applies to

Related Waits

See Also

• More About LCK_M_SIU_ABORT_BLOCKERS