Wait Type BROKER_DISPATCHER

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, wait types provide insights into where processes might be delayed. One such wait type, BROKER_DISPATCHER, is specific to Service Broker, a feature in SQL Server used for asynchronous messaging and queuing. The BROKER_DISPATCHER wait type occurs when the Service Broker dispatcher is idle, waiting for tasks to process. In this blog post, we’ll explain what the BROKER_DISPATCHER wait type means, when it occurs, and whether it should be a cause for concern.

What Is the BROKER_DISPATCHER Wait Type?

The BROKER_DISPATCHER wait type occurs when a Service Broker dispatcher thread is waiting for tasks to process. A dispatcher thread is responsible for managing Service Broker’s internal operations, such as message delivery and queue activation. When there are no active messages or tasks to process, the dispatcher becomes idle, and the BROKER_DISPATCHER wait type is recorded.

This wait type is typically benign and reflects idle time rather than a performance issue. It is expected in environments where Service Broker is enabled but not actively processing messages.

When Does BROKER_DISPATCHER Appear?

The BROKER_DISPATCHER wait type is common in systems that use Service Broker but may not have constant message activity. Scenarios where this wait type may appear include:

• Idle Service Broker – When no messages are being sent or processed, the dispatcher threads will wait for tasks, resulting in this wait type.
• Low Message Activity – In systems with sporadic Service Broker usage, dispatcher threads may frequently enter an idle state.
• Enabled but Unused Service Broker – If Service Broker is enabled but not actively utilized, dispatcher threads will show this wait type as they wait for activity.

This wait type is generally not a cause for concern unless Service Broker is expected to be actively processing messages but isn’t functioning as intended.

Should You Worry About BROKER_DISPATCHER Waits?

In most cases, BROKER_DISPATCHER waits are harmless and simply indicate that dispatcher threads are idle. However, if you notice excessive waits alongside other issues, such as delayed message delivery or blocked queues, it could signal a potential problem with Service Broker configuration or performance. Possible causes include:

• Misconfigured Service Broker – Incorrectly set up endpoints, routes, or activation procedures may prevent messages from being processed.
• Blocked Queues – If messages are stuck in queues due to blocked sessions or processing errors, dispatcher threads may remain idle.
• Application Design Issues – An application not sending messages as expected may lead to unused dispatcher threads.

How to Address BROKER_DISPATCHER Waits

If you suspect issues with Service Broker related to BROKER_DISPATCHER waits, consider the following steps to investigate and resolve the problem:

• Check Service Broker Configuration – Verify that Service Broker is configured correctly, including endpoints, routes, and security settings.
• Monitor Queues – Use system views such as sys.transmission_queue and sys.service_queues to check for messages stuck in queues or processing delays.
• Test Application Integration – Ensure that the application using Service Broker is sending messages as intended and that the target queues are set up properly.
• Review Activation Procedures – If queues use activation stored procedures, ensure that they are functioning correctly and not encountering errors.
• Monitor System Performance – Ensure that SQL Server has sufficient resources (CPU, memory, and disk) to handle Service Broker operations efficiently.

Conclusion

The BROKER_DISPATCHER wait type in SQL Server indicates that Service Broker dispatcher threads are idle, waiting for tasks to process. In most cases, this wait type is normal and does not require action. However, if Service Broker is expected to be actively processing messages and BROKER_DISPATCHER waits are excessive, it may point to configuration or application issues that need attention. By monitoring queues, verifying configurations, and testing application integration, you can ensure Service Broker operates as intended.

If you need expert help with SQL Server performance tuning, Service Broker configuration, or resolving wait type issues, Stedman Solutions offers managed services to keep your SQL Server environment running efficiently and reliably.

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Applies to

Related Waits

See Also

• More About BROKER_DISPATCHER