sys.dm_os_threads (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
Returns a list of all SQL Server Operating System threads that are running under the SQL Server process.
Note
To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_os_threads. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.
| Column name | Data type | Description |
|---|---|---|
| thread_address | varbinary(8) | Memory address (Primary Key) of the thread. |
| started_by_sqlservr | bit | Indicates the thread initiator. 1 = SQL Server started the thread. 0 = Another component started the thread, such as an extended stored procedure from within SQL Server. |
| os_thread_id | int | ID of the thread that is assigned by the operating system. |
| status | int | Internal status flag. |
| instruction_address | varbinary(8) | Address of the instruction that is currently being executed. |
| creation_time | datetime | Time when this thread was created. |
| kernel_time | bigint | Amount of kernel time that is used by this thread. |
| usermode_time | bigint | Amount of user time that is used by this thread. |
| stack_base_address | varbinary(8) | Memory address of the highest stack address for this thread. |
| stack_end_address | varbinary(8) | Memory address of the lowest stack address of this thread. |
| stack_bytes_committed | int | Number of bytes that are committed in the stack. |
| stack_bytes_used | int | Number of bytes that are actively being used on the thread. |
| affinity | bigint | CPU mask on which this thread is running. This depends on the value configured by the ALTER SERVER CONFIGURATION SET PROCESS AFFINITY statement. Might be different from the scheduler in case of soft-affinity. |
| Priority | int | Priority value of this thread. |
| Locale | int | Cached locale LCID for the thread. |
| Token | varbinary(8) | Cached impersonation token handle for the thread. |
| is_impersonating | int | Indicates whether this thread is using Win32 impersonation. 1 = The thread is using security credentials that are different from the default of the process. This indicates that the thread is impersonating an entity other than the one that created the process. |
| is_waiting_on_loader_lock | int | Operating system status of whether the thread is waiting on the loader lock. |
| fiber_data | varbinary(8) | Current Win32 fiber that is running on the thread. This is only applicable when SQL Server is configured for lightweight pooling. |
| thread_handle | varbinary(8) | Internal use only. |
| event_handle | varbinary(8) | Internal use only. |
| scheduler_address | varbinary(8) | Memory address of the scheduler that is associated with this thread. For more information, see sys.dm_os_schedulers (Transact-SQL). |
| worker_address | varbinary(8) | Memory address of the worker that is bound to this thread. For more information, see sys.dm_os_workers (Transact-SQL). |
| fiber_context_address | varbinary(8) | Internal fiber context address. This is only applicable when SQL Server is configured for lightweight pooling. |
| self_address | varbinary(8) | Internal consistency pointer. |
| processor_group | smallint | Applies to: SQL Server 2008 R2 (10.50.x) and later. Processor group ID. |
| pdw_node_id | int | Applies to: Azure Synapse Analytics, Analytics Platform System (PDW) The identifier for the node that this distribution is on. |
Permissions
On SQL Server and SQL Managed Instance, requires VIEW SERVER STATE permission.
On SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account, the Microsoft Entra admin account, or membership in the ##MS_ServerStateReader## server role is required. On all other SQL Database service objectives, either the VIEW DATABASE STATE permission on the database, or membership in the ##MS_ServerStateReader## server role is required.
Permissions for SQL Server 2022 and later
Requires VIEW SERVER PERFORMANCE STATE permission on the server.
Notes on Linux version
Due to how the SQL engine works in Linux, some of this information doesn't match Linux diagnostics data. For example, os_thread_id does not match the result of tools like ps,top or the procfs (/proc/pid). This is due the Platform Abstraction Layer (SQLPAL), a layer between SQL Server components and the operating system.
Examples
Upon startup, SQL Server starts threads and then associates workers with those threads. However, external components, such as an extended stored procedure, can start threads under the SQL Server process. SQL Server has no control of these threads. sys.dm_os_threads can provide information about rogue threads that consume resources in the SQL Server process.
The following query is used to find workers, along with time used for execution, that are running threads not started by SQL Server.
Note
For conciseness, the following query uses an asterisk (*) in the SELECT statement. You should avoid using the asterisk (*), especially against catalog views, dynamic management views, and system table-valued functions. Future upgrades and releases of Microsoft SQL Server may add columns and change the order of columns to these views and functions. These changes might break applications that expect a particular order and number of columns.
SELECT *
FROM sys.dm_os_threads
WHERE started_by_sqlservr = 0;
See also
sys.dm_os_workers (Transact-SQL)
SQL Server Operating System Related Dynamic Management Views (Transact-SQL)