![]() ![]() IF (OBJECT_ID('dbo.Historico_Deadlocks') IS NULL) Passo 5 - Vou tentar travar a Tabela (já possui lock na outra sessão) Passo 6 - Ao tentar travar a Tabela 1, irá ocorrer o deadlock If there are still deadlocks in the instance, it will eliminate more sessions and shorten the next execution cycles in 100ms (each cycle) until no deadlock is detected. When the Deadlock Monitor Thread drops a session due to deadlock, it runs again immediately to verify that the deadlock has been resolved. ![]() If the sessions have the same priority and the same cost, the victim of the deadlock will be chosen at random. How does SQL Server decide which session it will drop? It is very simple, it will always eliminate the session that has the lowest cost (generally, the one that was “locked” last), thus facilitating the rollback of transactions performed by the session that was chosen to be disconnected (deadlock victim) As long as they have the same priority. If it encounters any deadlock, it will kill one of the deadlocked sessions to free the locked resources for the other waiting session. This thread fires every 5 seconds to check for deadlocks on the instance. If you query the sys.dm_os_waiting_tasks DMV, you will notice that there is always a system task with the REQUEST_FOR_DEADLOCK_SEARCH event. In SQL Server there is a feature called Deadlock Monitor Thread, which runs in the background to identify and “help” resolve deadlocks in the instance, thus preventing the sessions from endlessly waiting for each other. Career, Courses and Certifications (35).
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