'Lock request time out period exceeded' when connecting to the database from SSMS
Published May 19 2021 09:48 AM 6,820 Views

When you connect to the database using SQL Server Management Studio (SSMS), It will perform several queries to gather the information necessary for the user interface. If one of the queries performed by SSMS is blocked, you may face a lock time-out in the connection:




You can use the PowerShell script below, while attempting to connect, to identify the session that is causing the block:


Note: It is necessary to set values for the highlighted variables. It will create CSVs with the result of the queries in the $OutputFolder.


#Connect to SQL and run QUERY

$SQLServer = ""

$SQLDBName = ""

$SQLUsername = ""

$SQLPassword = ""

$OuputFolder = "C:"


#To get information about sessions that are blocking and being blocked

$SqlQuery = "SELECT current_timestamp as [CURRENT_TIMESTAMP]

       , DB_NAME(dtl.resource_database_id) AS database_name

       , req.session_id AS blocked_sessionID

       , ses.program_name blocked_programName

       , ses.host_name blocked_hostname

       , ses.login_name blocked_login

       , CASE ses.transaction_isolation_level

              WHEN 1 THEN 'ReadUncomitted'

              WHEN 2 THEN 'ReadCommitted'

              WHEN 3 THEN 'Repeatable'

              WHEN 4 THEN 'Serializable'

              WHEN 5 THEN 'Snapshot'

       END blocked_isolation_level

       , REPLACE(REPLACE(sqltext.TEXT, CHAR(13), ' '), CHAR(10), ' ') AS blocked_last_query

       , req.status AS [blocked_status]

       , req.command AS blocked_command

       , req.cpu_time AS blocked_cpuTime

       , req.total_elapsed_time AS blocked_totalElapsedTime

       , blocked_tran.transaction_id blocked_transaction_id

       , osw.blocking_session_id AS blocker_SessionID

       , blocker_ses.program_name blocker_programName

       , blocker_ses.host_name blocker_hostName

       , blocker_ses.login_name blocker_login

       , CASE blocker_ses.transaction_isolation_level

              WHEN 1 THEN 'ReadUncomitted'

              WHEN 2 THEN 'ReadCommitted'

              WHEN 3 THEN 'Repeatable'

              WHEN 4 THEN 'Serializable'

              WHEN 5 THEN 'Snapshot'

       END blocker_isolation_level

       , REPLACE(REPLACE(iif(blocker_sqltext.TEXT is NULL,blocker_sqltext2.event_info,blocker_sqltext.TEXT), CHAR(13), ' '), CHAR(10), ' ') AS blocker_last_query

       , blocker_req.status AS [blocker_status]

       , blocker_req.command AS blocker_command

       , blocker_req.cpu_time AS blocker_cpuTime

       , blocker_req.total_elapsed_time AS blocker_totalElapsedTime

       , blocker_proc.lastwaittype blocker_last_waittype

       , blocker_proc.last_batch blocker_last_batch

       , blocker_proc.open_tran blocker_open_tran

       , blocker_tran.transaction_id blocker_transaction_id

       , blocker_proc.cmd blocker_command

       , dtl.request_mode AS lockRequestMode

       , dtl.resource_type AS lockResourceType

       , dtl.resource_subtype AS lockResourceSubType

       , osw.wait_type AS taskWaitType

       , osw.resource_description AS taskResourceDescription

       , osw.wait_duration_ms

FROM sys.dm_exec_requests req

INNER JOIN sys.dm_exec_sessions ses on ses.session_id = req.session_id

CROSS APPLY sys.dm_exec_sql_text(req.sql_handle) AS sqltext

INNER JOIN sys.dm_tran_locks dtl on dtl.request_session_id = req.session_id

INNER JOIN sys.dm_os_waiting_tasks osw on osw.session_id = req.session_id

LEFT JOIN sys.dm_tran_session_transactions blocked_tran on blocked_tran.session_id =req.session_id

INNER JOIN dbo.sysprocesses blocker_proc on osw.blocking_session_id = blocker_proc.spid

LEFT JOIN sys.dm_exec_requests blocker_req on blocker_req.session_id = osw.blocking_session_id

LEFT JOIN sys.dm_exec_sessions blocker_ses on blocker_ses.session_id = osw.blocking_session_id

LEFT JOIN sys.dm_tran_session_transactions blocker_tran on blocker_tran.session_id =osw.blocking_session_id

OUTER APPLY sys.dm_exec_sql_text(blocker_req.sql_handle) AS blocker_sqltext

OUTER APPLY sys.dm_exec_input_buffer(osw.blocking_session_id,0) as blocker_sqltext2;"


#To get the locks that are being held by the sessions that are blocking and being blocked

$SqlQuery2 = "

select DB_NAME(locks.resource_database_id) AS database_name

 , locks.request_session_id

 , locks.resource_type, locks.resource_subtype

 , locks.resource_description

 , locks.resource_associated_entity_id

 , locks.resource_lock_partition

 , locks.request_mode

 , locks.request_type

 , locks.request_status

 , locks.request_reference_count

 , locks.request_lifetime

 , locks.request_exec_context_id

 , locks.request_request_id

 , locks.request_owner_type

FROM sys.dm_exec_requests req

INNER JOIN sys.dm_os_waiting_tasks osw on osw.session_id = req.session_id

INNER JOIN sys.dm_tran_locks locks on osw.blocking_session_id = locks.request_session_id or (osw.session_id = locks.request_session_id and osw.blocking_session_id is not null)

order by locks.request_session_id;"


#Dummy query to test if queries are running successfully, in case the previous ones do not return data

$SqlQuery3 = "select CURRENT_TIMESTAMP as timestamp, @@SERVERNAME as server_name, DB_NAME() as database_name, @@SPID as session_id;"


#Connect to SQL Server

$SqlConnection = New-Object System.Data.SqlClient.SqlConnection

$SqlConnection.ConnectionString = "Server = $SQLServer; Database = $SQLDBName; User ID = $SQLUsername; Password = $SQLPassword"


$SqlCmd = New-Object System.Data.SqlClient.SqlCommand

$SqlCmd.Connection = $SqlConnection


#Create the objects that will be used to run the queries

$SqlAdapter = New-Object System.Data.SqlClient.SqlDataAdapter


#Run 1st query

$DataSet = New-Object System.Data.DataSet

$SqlCmd.CommandText = $SqlQuery

$SqlAdapter.SelectCommand = $SqlCmd



#Output RESULTS of 1st query to CSV

$DataSet.Tables[0] | Export-Csv -Delimiter ';' -Path "$OuputFolder\lock_waits_$(get-date -f yyyy-MM-dd-HH.mm.ss).csv" -NoTypeInformation


#Run 2nd query

$DataSet = New-Object System.Data.DataSet

$SqlCmd.CommandText = $SqlQuery2

$SqlAdapter.SelectCommand = $SqlCmd



#Output RESULTS of 2nd query to CSV

$DataSet.Tables[0] | Export-Csv -Delimiter ';' -Path "$OuputFolder\lock_list_$(get-date -f yyyy-MM-dd-HH.mm.ss).csv" -NoTypeInformation


#Run 3rd query

$DataSet = New-Object System.Data.DataSet  

$SqlCmd.CommandText = $SqlQuery3

$SqlAdapter.SelectCommand = $SqlCmd



#Output RESULTS of 3rd query to CSV

$DataSet.Tables[0] | Export-Csv -Delimiter ';' -Path "$OuputFolder\test_connection_$(get-date -f yyyy-MM-dd-HH.mm.ss).csv" -NoTypeInformation


#Close the connection




In the CSV files, you should be able to see the last queries of the sessions involved in the block, their isolation level, if they are inside a transaction and the locks they are holding. This should help you understand why the block is happening.


This PowerShell script uses two queries from this blog post. Please refer to this blog post for additional information.





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‎May 19 2021 09:48 AM
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