Getting some weird behavior here I ve recently introduced Hi

Question

Getting some weird behavior here I ve recently introduced HikariCP as a new DataSource to make use of connection pooling The service was running smoothly for a few days then suddenly any call sprayed the exception in the attached snippet all over the place Restarting the service immediately started to do the same only rolling it back to an earlier version without HikariCP fixed the issue Any idea where to start looking

robin · Answer

My biggest confusion comes from the error message itself shouldn t Hikari automatically restart closed connections and only hand out open connections This seems to me like some connection is kept cached somewhere and reused beyond its lifetime But then why would the error appear again immediately after restarting the service with presumably all new connections

tapac · Answer

Do you use coroutines in your code

robin · Answer

Yes we do We re running a Ktor Server with Exposed as the Backend But we re using only the blocking `transaction` functions not the suspend or async ones and not switching Threads or dispatchers from inside a transaction as far as I can tell so the code inside of transactions should run fully blocking right

tapac · Answer

Do you use other suspend functions inside transaction block

robin · Answer

Not that I know of but can t be completely sure right now What would we need to do to make it work if we did

tapac · Answer

Try to replace `transaction` with `suspendedTransaction` or `newSuspendedTransaction`

robin · Answer

I will try that thanks

robin · Answer

Looking good so far One thing tripped us up on the way though simply replacing all calls to `transaction` with `newSuspendedTransaction` was not enough as the latter doesn t automatically check if there s a transaction already in scope which to attach to and always creates a completely new transaction instead leading to outer transactions not being able to see changes made by inner transactions We solved that by implementing our own `transaction` function that checks for an already open transaction in the coroutine context and delegates to `suspendedTransaction` or `newSuspendedTransaction` accordingly I was surprised that exposed doesn t seem to have that functionality is this a conscious omission or something you would welcome a pull request for Our implementation isn t that elaborate it wouldn t be much work to integrate it into exposed itself so that we can have a true suspending pendant to `transaction`

robin · Answer

If you like I can create an issue about that were we can discuss the details