Does dead lock cause timeout issue in sql server 2017?

Question

Does dead lock cause timeout issue in sql server 2017?

kumar-9444 121

Application is facing timeout issue . when we checked from sql server(2017) end, we found dead lock in sql server . Will this caused to timeout?

Anonymous

2023-08-17T06:03:54.38+00:00

Hi,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.
Anonymous

2023-08-30T09:14:51.6433333+00:00

Hi,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.

3 answers

Your answer

Anonymous

2023-08-17T06:03:54.38+00:00

Hi,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.
Anonymous

2023-08-30T09:14:51.6433333+00:00

Hi,

We have not received a response from you. Did the reply could help you? If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. By doing so, it will benefit all community members who are having this similar issue. Your contribution is highly appreciated.

Answer 1

Dan Guzman 9,401

Long-term blocking may cause query timeouts but deadlocks typically do not because SQL server will rollback one of the sessions involved before queries timeout.

Deadlocks and blocking are often a symptom that query/index tuning is needed. Inefficient queries scan more data than needed. Not only do inefficient queries take longer to run, they lock more data which increases the likelihood of deadlocks/blocking with concurrent queries.

Erland Sommarskog 121.4K Reputation points MVP Volunteer Moderator

2023-08-11T21:15:49.1933333+00:00

I have seen situations where deadlocks caused timeouts. This was situations were there were very many processes in a deadlock, and SQL Server would kill one process, and then five seconds later find that there was still a deadlock and kill the next one. It took more than a minute before the deadlock was entirely resolved. Since the default timeout is 30 seconds, this may have resulted in some timeouts.

But for a plain simple deadlock with two processes, it is not likely that a deadlock alone would result in a timeout, because SQL Server checks for deadlocks every five seconds.
Dan Guzman 9,401 Reputation points

2023-08-12T11:09:51.51+00:00

@Erland Sommarskog , I said "typically" in my answer to describe the common case where 2 processes are involved. But you are right that timeouts can occur when more sessions are involved in a blocking episode with more than one deadlock.

Answer 2

Javier Villegas 900 MVP

Additionally to what Dan has mentioned you can create an Extended Events Session on your instance to detect the timeouts

See this question which was answered and provide an example of how to create the session

Answer 3

Anonymous

Hi @kumar-9444

As a supplement, you can refer to the deadlock guide.

https://learn.microsoft.com/en-us/sql/relational-databases/sql-server-deadlocks-guide?view=sql-server-2017

Best regards,

Percy Tang

Share via

Does dead lock cause timeout issue in sql server 2017?

3 answers

Your answer