Deadlocked on lock resources with another process and has been chosen as the deadlock victim

Flowable Engine
1

This I get intermittent and rare, when calling CmmnRuntimeService.startPlanItemInstance.
Any idea? I will investigate too.

Thank You!

2

Hey @barry731,

Are you using SQL Server by any chance?

This issue can occur when there is resource contention on the source MS SQL database, which causes the database to select a victim (process) to kill to free up resources. SQL servers keep an internal row count when database threads access rows. A deadlock exception is thrown by sql server when too many such threads are accessing it.

Generally, provisioning the database with better hardware solves the problem.

Cheers,
Filip

3

Hi Filip,

yes we are using MS SQL Server.
So this is a know issue and not releated using flowable engine with incorrect API usage?

Thank You!
Barry

4

Yes this is known for SQL Server. If your database server is overwhelmed it can start throwing this exceptions. Using better hardware for the Database solves this problem.

Cheers,
Filip

5

Hi @filiphr,
SQL Server, by default, creates clustered indexes on primary keys, and Flowable uses GUIDs for primary keys.
Could be possible that the downsides for using GUID as clustering keys [1] have such an impact on performances that then leads to the high resource contention that causes the deadlocks?

Thanks,
marco

[1]
https://stackoverflow.com/questions/11938044/what-are-the-best-practices-for-using-a-guid-as-a-primary-key-specifically-rega
https://blog.novanet.no/careful-with-guid-as-clustered-index/