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SQL Server Kill Process


SQL Server Kill PRocess By Mike Bennyhoff

For SQL Server users, there are a variety of tools available to terminate process operations. The typical go-to involves connecting to the server via Management Studio and utilizing the Activity Monitor for selection purposes. Alternatively, you can execute "KILL" commands with specific Process IDs or use prior versions' extended stored procedures (e.g., xp_terminate_process). Whichever method you choose, it is important that all processes be terminated carefully and correctly when necessary.


STOP - Kill Stuff In SQL Server

Using SQL Server Management Studio (SSMS) To Kill A Background Process

To kill a process in SQL Server using SQL Server Management Studio (SSMS), you can follow these steps:


  • Open SSMS and connect to the SQL Server instance.

  • In the Object Explorer, expand the "Management" node and click on "Activity Monitor".

  • In the Activity Monitor window, you will see a list of all processes that are currently running on the server. You can filter the list by database, user, or status to find the process you want to kill.

  • Right-click on the process you want to kill and select "Kill Process" from the context menu.

  • A dialog box will appear, asking you to confirm the action. Click "Yes" to kill the process.


Using T-SQL To Kill A Process

You can also use T-SQL to use the kill a process. You will need to know the SPID (Server Process ID) of the process you want to terminate. You can use the sp_who or sp_who2 to find the SPID as shown below. When we execute SP_Who2 we can see the SPID (in yellow)


Active Processes In SQL Server

Now we can execute the kill command to kill a process with a SPID of 123, you can use the following command:

--Sample Code
Kill 1;
Kill 2;

Will My Process Stop Instantly?

Nope, SQL Server has to roll back your process, and this will take some time. The more complex the process, the longer it will take to roll-back. If you are concerned, take the roll-back will take too much time you can get an estimate of the time it might SQL Server to roll back a process by using the sys.dm_exec_requests DMV to check the percent_complete column for the process. command


Here is more information on how to use the sys_exec_requests DMV


Percent Complete Estimate

The percent_complete This column indicates the percentage of the rollback that has been completed. You can use this information to estimate the time it will take for the rollback to complete.


For example, if the percent_complete value is 50%, you can estimate that it will take approximately twice as long for the rollback to complete as it has already taken. However, it's important to note that this is just an estimate and the actual time it takes for the rollback to complete may be different. In addition, the roll-back may also be blocked by another process. Please see my blog on Blocking and Locking for more Information on that topic.


Logging What Processes Have Been Killed

Killing a process in SQL Server is logged. When a process is killed in SQL Server, an entry is added to the SQL Server error log indicating that the process was terminated. The entry includes the SPID (server process ID) of the process that was killed, as well as the login name of the user who killed the process.


SQL Server Logs

To view the SQL Server error log, you can use SQL Server Management Studio (SSMS) and navigate to the "Management" node and then click on "SQL Server Logs". Alternatively, you can use the xp_readerrorlog system stored procedure to view the error log.


Negative Side Effects

The kill command should be used with caution, as it can cause data loss or other issues if used improperly. This command is typically ONLY used when a session or process is stuck or not responding, and needs to be terminated in order to free up resources or resolve other issues. You should only use the kill command after you have confirmed that the session or process you are trying to terminate is not critical to the operation of your system, and that no other users or processes are dependent on it.


Using the kill command in SQL Server can have several negative effects, including:

  • Data loss: If the session or process being terminated is in the middle of a transaction, the transaction may be rolled back, resulting in data loss.

  • Deadlocks: Killing a process that is involved in a deadlock can cause other processes to be blocked indefinitely.

  • Data corruption: Terminating a process that is writing to a database file or log can cause the file or log to become corrupted.Unintended consequences: Killing a process that is performing a critical function can cause unexpected consequences that are difficult to diagnose and fix.

  • Dependent processes: Killing a process that is necessary for other processes to function can cause them to fail as well.


Errors That Might Occure When Killing A Process

When SQL Server detects a deadlock and chooses to kill a process, it will rollback the transaction of the killed process and the following error message may be generated:

  • Error 1205: "Transaction (Process ID) was deadlocked on {lock resource} with another process and has been chosen as the deadlock victim. Rerun the transaction." This message indicates that the transaction has been rolled back due to a deadlock and should be rerun.

  • Error 1222: "Transaction (Process ID) was deadlocked on {lock resource} with another process and has been chosen as the deadlock victim. Rerun the transaction." This message is similar to error 1205, but it indicates that the deadlock was caused by a lock request that was not compatible with an existing lock.

  • Error 3960 : "Deadlock found when trying to get lock; try restarting transaction" This message indicates that a deadlock has been detected and it was not possible to determine which transaction should be rolled back. Additionally, in some cases, the process that has been killed may have been running for an extended period of time, so the following error message may also be generated:

  • Error 701: "There is insufficient system memory to run this query." This message indicates that the system has run out of memory while trying to rollback the transaction, this can be due to the size of the transaction or the number of pages it has modified. It's also worth noting that if a deadlock occurs in a distributed transaction, the error message that is generated will be a MSDTC error message and not a SQL Server error message.


The Nuclear Option(s)

Killing All Of The Process In A Database

--Kill All Process In DBA Database 
--You can execite the printed output or uncomment the EXEC(SQL)

DECLARE @SQL as varchar(MAX) Set @SQL = ' '
DECLARE @spid Varchar(50)
DECLARE cur CURSOR FOR
SELECT Cast(spid as Varchar(50)) FROM sys.sysprocesses WHERE dbid = db_id('DBA')
OPEN cur
FETCH NEXT FROM cur INTO @spid
WHILE @@FETCH_STATUS = 0
BEGIN
    Set @SQL = @SQL + 'EXEC('+Char(39)+'KILL '+@spid+'); ' 
    Print @SQL
    --EXEC(@SQL)
FETCH NEXT FROM cur INTO @spid
END
CLOSE cur
DEALLOCATE cur

Stopping and Starting SQL Server

Stopping and restarting the SQL Server service will terminate all existing connections and processes, including all SPIDs (system process IDs). When the SQL Server service is stopped, all active connections to the databases are immediately disconnected, and any running transactions or queries are rolled back. When the SQL Server service is restarted, it starts fresh, and all existing connections are lost. It's also important to take into consideration the implications of stopping and restarting the SQL Server service on the availability of your databases, as the service will be unavailable while it's being stopped and restarted.

It's recommended to use the SQL Server Management Studio (SSMS) to stop and start the service. In the Object Explorer, expand the server, right-click on the SQL Server service and select Stop/Start.


SQL Server Object Explorer

If you have to stop and start the SQL Server service, it's recommended to plan it during a maintenance window, when the impact on the system is minimal.


Do I Kill A Backup Job Or Do I Stop A Backup Job

Whether it's better to kill a SQL Server backup job or stop the job depends on the specific situation and the requirements for the backup.

Killing A Backup Job

Killing a backup job using the "KILL" command will immediately terminate the process without giving it the opportunity to clean up any resources or complete any pending transactions. This can cause data loss or other issues, and should only be used as a last resort.

Stopping A Backup Job

Stopping a backup job, on the other hand, gives the process the opportunity to clean up any resources and complete any pending transactions before stopping. This is generally considered a safer option, as it helps to minimize the risk of data loss or other issues.

If you are using SQL Server Agent to schedule backups, it's recommended to stop the job. It allows the backup process to complete the current backup and clean up any resources before stopping. This way, the backup process won't leave an incomplete or corrupt backup file.


This video shows how to stop a backup Job

How Do I Kill External Processes Started With XP_CMDShell?

In SQL Server, you can use the extended stored procedure "xp_cmdshell" to execute command prompt commands, including commands to kill external processes. The "xp_cmdshell" stored procedure allows you to run the command-line tools that are available on the server where SQL Server is installed.

xp_cmdshell

To kill an external process that was started with "xp_cmdshell," you can use the "TASKKILL" command in conjunction with the "xp_cmdshell" stored procedure. The "TASKKILL" command is used to end one or more processes, and it can be passed a process ID or the name of the process.

Here's an example of how you can use "xp_cmdshell" and "TASKKILL" to kill a process with a specific process ID:

EXEC xp_cmdshell 'TASKKILL /PID 12345 /F'
TaskKill

his command will execute the "TASKKILL" command with the "/PID" option, specifying the process ID of the process you want to kill, and the "/F" option, which tells "TASKKILL" to forcefully terminate the process.


In Windows, you can find the process ID (PID) number of a running process in several ways:

  • Using the Task Manager: Press the Ctrl + Shift + Esc keys to open the Task Manager. In the "Details" tab, you will see a column labeled "PID" that displays the process ID of each running process.

  • Using the command prompt: Open the command prompt and type "tasklist" to see a list of running processes. The "PID" column displays the process ID of each process. To filter the list by process name, use the command "tasklist /fi "imagename eq process_name"

  • Using the PowerShell: Open PowerShell and type "Get-Process" to see a list of running processes. The "Id" column displays the process ID of each process. To filter the list by process name, use the command "Get-Process -Name process_name"

  • Using the Resource Monitor: Press the Windows key + R and type "resmon" to open the Resource Monitor. In the "Processes" tab, you will see a column labeled "PID" that displays the process ID of each running process.

Active Process In Windows Server

If The External Process Will NOT Stop


More Information

If you want to avoid the nuclear option or killing one spid at a time check out my SQL Server Maintenance and Management product. This DBA as software tool will help you avoid and detect problems before they rise to the level of killing and nuking.




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