Comment simuler une impasse dans SQL Server en un seul processus?

exécutez le script ci-dessous dans une fenêtre SQL Server Management Studio. (Testé sur 2008 R2 seulement.), Vous pouvez le laisser fonctionner aussi longtemps que nécessaire.

à l'endroit où vous voulez simuler une impasse, insérez un appel à sp_simulatedeadlock. Exécutez votre processus, et l'impasse devrait produire.

lorsque le test est terminé, arrêtez la requête SSMS et lancez le code de nettoyage en bas.

/*
This script helps simulate deadlocks.  Run the entire script in a SQL query window.  It will continue running until stopped.
In the target script, insert a call to sp_simulatedeadlock where you want the deadlock to occur.
This stored procedure, also created below, causes the deadlock.
When you are done, stop the execution of this window and run the code in the cleanup section at the bottom.
*/
set nocount on

if object_id('DeadlockTest') is not null
    drop table DeadlockTest

create table DeadlockTest
(
    Deadlock_Key int primary key clustered,
    Deadlock_Count int
)
go

if exists (select * from sysobjects where id = object_id(N'sp_simulatedeadlock')
           AND objectproperty(id, N'IsProcedure') = 1)
drop procedure sp_simulatedeadlock
GO

create procedure sp_simulatedeadlock
(
    @MaxDeadlocks int = -1 -- specify the number of deadlocks you want; -1 = constant deadlocking
)
as begin

    set nocount on

    if object_id('DeadlockTest') is null
        return

    -- Volunteer to be a deadlock victim.
    set deadlock_priority low

    declare @DeadlockCount int

    select @DeadlockCount = Deadlock_Count -- this starts at 0
    from DeadlockTest
    where Deadlock_Key = 2

    -- Trace the start of each deadlock event.
    -- To listen to the trace event, setup a SQL Server Profiler trace with event class "UserConfigurable:0".
    -- Note that the user running this proc must have ALTER TRACE permission.
    -- Also note that there are only 128 characters allowed in the trace text.
    declare @trace nvarchar(128)

    if @MaxDeadlocks > 0 AND @DeadlockCount > @MaxDeadlocks
    begin

        set @trace = N'Deadlock Test @MaxDeadlocks: ' + cast(@MaxDeadlocks as nvarchar) + N' @DeadlockCount: ' + cast(@DeadlockCount as nvarchar) + N' Resetting deadlock count.  Will not cause deadlock.'
        exec sp_trace_generateevent
            @eventid = 82,  -- 82 = UserConfigurable:0 through 91 = UserConfigurable:9
            @userinfo = @trace

        -- Reset the number of deadlocks.
        -- Hopefully if there is an outer transaction, it will complete and persist this change.
        update DeadlockTest
        set Deadlock_Count = 0
        where Deadlock_Key = 2
        return
    end

    set @trace = N'Deadlock Test @MaxDeadlocks: ' + cast(@MaxDeadlocks as nvarchar) + N' @DeadlockCount: ' + cast(@DeadlockCount as nvarchar) + N' Simulating deadlock.'
    exec sp_trace_generateevent
        @eventid = 82,  -- 82 = UserConfigurable:0 through 91 = UserConfigurable:9
        @userinfo = @trace

    declare @StartedTransaction bit
    set @StartedTransaction = 0
    if @@trancount = 0
    begin
        set @StartedTransaction = 1
        begin transaction
    end

    -- lock 2nd record
    update DeadlockTest
    set Deadlock_Count = Deadlock_Count
    from DeadlockTest
    where Deadlock_Key = 2

    -- lock 1st record to cause deadlock
    update DeadlockTest
    set Deadlock_Count = Deadlock_Count
    from DeadlockTest
    where Deadlock_Key = 1

    if @StartedTransaction = 1
        rollback    
end
go

insert into DeadlockTest(Deadlock_Key, Deadlock_Count)
select 1, 0
union select 2, 0

-- Force other processes to be the deadlock victim.
set deadlock_priority high

begin transaction

while 1 = 1
begin

    begin try

        begin transaction

        -- lock 1st record
        update DeadlockTest
        set Deadlock_Count = Deadlock_Count
        from DeadlockTest
        where Deadlock_Key = 1

        waitfor delay '00:00:10'

        -- lock 2nd record (which will be locked when the target proc calls sp_simulatedeadlock)
        update DeadlockTest
        set Deadlock_Count = Deadlock_Count
        from DeadlockTest
        where Deadlock_Key = 2

        rollback

    end try
    begin catch
        print 'Error ' + convert(varchar(20), ERROR_NUMBER()) + ': ' + ERROR_MESSAGE()
        goto cleanup
    end catch

end

cleanup:

if @@trancount > 0
    rollback

drop procedure sp_simulatedeadlock
drop table DeadlockTest