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sys.dm_os_threads (Transact-SQL)

Returns a list of all SQL Server Operating System threads that are running under the SQL Server process.

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

Stores the processor group ID.

Requires VIEW SERVER STATE permission on the server.

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.

NoteNote

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;
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