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.


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.


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.


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.


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.

  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)