![]() ![]() SQL Server aborts the transaction of one of the involved processes. When the LOCK_MONITOR detects a deadlock, Requests exist between the processes holding locks and the processes The LOCK_MONITOR thread checks for deadlocks byĮxamining the list of waiting lock requests to see if any circular lock Pass, this process detects all the processes that are waiting on a lock A separate process in SQL Server, called LOCK_MONITOR,Ĭhecks the system for deadlocks roughly every 5 seconds. ![]() SQL Server automatically detects when a deadlock situation occurs. Deadlock scenario due to locks on index keys. Figure 5 depicts a scenario in which a deadlock occurs due to contention at the index key level. In fact, deadlocks often occur at the index It is often assumed that deadlocks happen at the data An example of a conversionĭeadlock is shown in Figure 4. Until the other releases the shared lock. Promote the shared lock to an exclusive lock, but neither can do so Shared lock on the same resource within a transaction and each wants to Simultaneously, Process 2 requests anĮxclusive lock on page 1:201, and a deadlock, or “deadly embrace,”Ī conversion deadlock occurs when two or more processes each hold a The same time, Process 2 acquires an exclusive lock on page 1:301 in aġ then attempts to acquire a lock on page 1:301 and begins waiting for Process 1 acquires an exclusive lock on page 1:201 in a transaction. Figure 3 demonstrates an example of a cycle deadlock. Resources, and then each needs to acquire a lock on the resource that Two primary types of deadlocks can occur in SQL Server:Ī cycle deadlock occurs when two processes acquire locks on different Other one completes, and neither one can complete until it can move Essentially, neither process can move forward until the Release the lock it is currently holding until it can receive the Receives the requested lock on the resource, and neither process can Neither process can move forward until it When two processes are each waiting for a locked resource that the other ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |