![]() Some extra environment information: Microsoft SQL Server 2019 (RTM-CU18) (KB5017593). We have double-checked the database configuration settings of the application to ensure that no specific settings related to deadlocks were enabled. We are unsure of how to approach this issue, since the cause is unknown to us, but we can definitively confirm that it is specific to our application. Its cpu_time keeps growing a by a couple of milliseconds every 10 seconds.įinally, here is the result of running sp_who2 for the affected database: There are 3 differences, but they are only in the waittime values:Īdditionally, from the sys.dm_exec_requests, we see that the deadlock victim (spid = 223) is never actually stopped. The deadlock graph XML: int)SELECT t2.ID, t2.BAT_RUNTIME_SECONDS, t2.BATCH_ID, t2.READS, t2.CUTOFF, t2.CREATION_DATE, t2.DATA_HASH, t2.ENDTIME, t2.ENABLED, t2.DATA_ID, t2.ANALYSIS_DATA, t2.LAST_CHANGE, t2.NAME, t2.REF_ID, t2.UNIQUE_ID, t2.CONV_DATA, t2.PREVIOUS_GROUP_ID, t2.ANALYSIS_ID, t2.GROUP_ID FROM BAT_DATA_TASK t2 LEFT OUTER JOIN (BAT_DATA_COMPONENT t3 JOIN BAT_DATA_TASK_STATE t4 ON (t4.ID = t3.ID)) ON (t3.ID = t2.PREVIOUS_GROUP_ID), BAT_DATA t5, BAT_DATA_TASK_STATE t1, BAT_DATA_COMPONENT t0 WHERE ((((((t2.GROUP_ID = AND (t2.ANALYSIS_ID = AND (t2.BATCH_ID IS NULL)) AND (t2.ENABLED = AND ((t2.CUTOFF IS NULL) OR ((t2.CUTOFF IS NOT NULL) AND (t2.CUTOFF < AND (((t0.ID = t2.GROUP_ID) AND ((t1.ID = t0.ID) AND (t0.COMPONENT_TYPE = AND (t5.ID = t2.ANALYSIS_ID))) ORDER BY COALESCE(t2.ENDTIME, ASC, t2.LAST_CHANGE ASC OFFSET ROWS int)SELECT t2.ID, t2.BAT_RUNTIME_SECONDS, t2.BATCH_ID, t2.READS, t2.CUTOFF, t2.CREATION_DATE, t2.DATA_HASH, t2.ENDTIME, t2.ENABLED, t2.DATA_ID, t2.ANALYSIS_DATA, t2.LAST_CHANGE, t2.NAME, t2.REF_ID, t2.UNIQUE_ID, t2.CONV_DATA, t2.PREVIOUS_GROUP_ID, t2.ANALYSIS_ID, t2.GROUP_ID FROM BAT_DATA_TASK t2 LEFT OUTER JOIN (BAT_DATA_COMPONENT t3 JOIN BAT_DATA_TASK_STATE t4 ON (t4.ID = t3.ID)) ON (t3.ID = t2.PREVIOUS_GROUP_ID), BAT_DATA t5, BAT_DATA_TASK_STATE t1, BAT_DATA_COMPONENT t0 WHERE ((((((t2.GROUP_ID = AND (t2.ANALYSIS_ID = AND (t2.BATCH_ID IS NULL)) AND (t2.ENABLED = AND ((t2.CUTOFF IS NULL) OR ((t2.CUTOFF IS NOT NULL) AND (t2.CUTOFF < AND (((t0.ID = t2.GROUP_ID) AND ((t1.ID = t0.ID) AND (t0.COMPONENT_TYPE = AND (t5.ID = t2.ANALYSIS_ID))) ORDER BY COALESCE(t2.ENDTIME, ASC, t2.LAST_CHANGE ASC OFFSET ROWS int)DELETE FROM BAT_DATA_TASK WHERE (ID IN is a comparison of 3 deadlocks at: We are unsure what is causing this, and don’t understand why the transaction for the deadlock victim spid isn’t being rolled back? ![]() It selects the same spid as deadlock victim every time, but even the selected spid keeps running as well and holds many locks. It logs a deadlock about every 5 seconds, but unexpectedly, all spids involved in the deadlock keep running indefinitely. The “victim” session is chosen according to the session’s deadlock priority.We are experiencing an issue with Microsoft SQL Server where every few days of running our application against the database, it goes into a state where it keeps deadlocking. The value LOW corresponds to ?5, NORMAL (the default value) corresponds to 0, and HIGH corresponds to 5. There are 21 different priority levels, from ?10 to 10. You can affect which transaction the system chooses as the “victim” by using the DEADLOCK_PRIORITY option of the SET statement. (The other transaction is executed after that.) A programmer can handle a deadlock by implementing the conditional statement that tests for the returned error number (1205) and then executes the rolled-back transaction again. ![]() If both transactions in Example 13.5 are executed at the same time, the deadlock appears and the system returns the following output:Īs the output of Example 13.5 shows, the database system handles a deadlock by choosing one of the transactions as a “victim” (actually, the one that closed the loop in lock requests) and rolling it back. Therefore, Example 1 below uses the WAITFOR statement to pause both transactions for ten seconds to simulate the deadlock. The parallelism of processes cannot be achieved naturally using the smallsampledatabase, because every transaction in it is executed very quickly. (In general, several transactions can cause a deadlock by building a circle of dependencies.)Įxample 1 below shows the deadlock situation between two transactions. The first transaction has a lock on some database object that the other transaction wants to access, and vice versa. A SQL Server deadlock is a special concurrency problem in which two transactions block the progress of each other.
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