Crash after moving from Qt 5.9 to Qt 5.12

[FaCal]

Hi everybody!

I'm working on a porting from Qt 5.9.7 to Qt 5.12.5 . The application is connected to a db sqlite and it uses a QSqlDatabase class.
When using Qt 5.12.5, I see a crash in QSqlQuery prepare or in the exec methods. I tried to print the queries and every time the application crash in a different one. The queries seems to be correct.
In a deeper analysis, I saw that the same database connection is used in 2 threads at the same time (2 select queries) and I think this is the cause of the crash because the threads cannot share the connection (https://stackoverflow.com/questions/47457478/using-qsqlquery-from-multiple-threads).

My answer is: why did this never happen in Qt 5.9.7? Could be connected to the porting?

Best regards!
Fabio

[Christian Ehrlicher]

@FaCal said in Crash after moving from Qt 5.9 to Qt 5.12:

why did this never happen in Qt 5.9.7?

Because in 5.9 the thread check was not there and you got rare race conditions now and then.

[JonB]

@FaCal
As per the docs, you are indeed correct that you must not attempt to use a connection from different threads.

I don't imagine anyone will know specifically why you got away with it in one version of Qt but not in another. That's what threading issues can be like.

[FaCal]

Thank you a lot!

BR
Fabio