Check SQL Server Deadlock

Troubleshooting deadlocks in SQL Server requires identifying them and alerting database administrators every time they occur. This approach allows for immediate detection of lock waits that are part of a deadlock, eliminating the need to wait for the next deadlock search.

When a deadlock is detected, the detection interval drops from 5 seconds to as low as 100 milliseconds. The lock monitor thread periodically searches through all tasks in an instance of the database engine to identify deadlocks.

Multiple Active Result Sets (MARS) resources and parallel query execution-related resources participate in SQL Server's deadlock detection scheme. Certain types of resources, such as transactions holding locks on data, can cause blocking that may result in a deadlock.

When a deadlock occurs, SQL Server chooses one process as the victim to kill and roll back, typically the least expensive to roll back, allowing other processes to move forward. Processes themselves cannot resolve conflicts, and SQL Server will not allow them to continue indefinitely.

A deadlock is defined as a circular blocking chain where two or more processes holding locks on data are waiting for each other to complete before moving forward. This common issue in SQL Server can manifest as application slowness, error messages, or SELECT statements taking an abnormally long time to finish.

In the event of a deadlock, SQL Server may display an error message indicating that the transaction was deadlocked and has been chosen as the victim. The message will typically include the process ID and information about the resources involved in the deadlock.

To mitigate the impact of deadlocks on your database operations, it's essential to identify and address these issues promptly. By implementing a proactive approach to deadlock detection and resolution, you can minimize downtime and ensure optimal performance from your SQL Server instance.

Check sql server deadlock