`waitForAtLeastOneAvailableConnection` waits for total `borrowConnectionTimeout` reducing potential ability to borrow connection

[kyle-copeland]

Describe the bug When multiple threads attempt to grab database connections, Atomikos will at most attempt to grow the pool twice before failing, regardless of the borrowConnectionTimeout.

To Reproduce Steps to reproduce the behavior:

1. Thread A attempts to grab a database connection
2. Thread A can't find one and grows the connections available
3. Thread B takes that connection
4. Thread A will wait for the remainder of borrowConnectionTimeout in waitForAtLeastOneAvailableConnection
5. Thread A will loop and perform steps 1,2,4 again
6. Thread C will take that connection
7. Thread A will exit in waitForAtLeastOneAvailableConnection

What you were doing (or trying to do): When our app boots, we spin up multiple worker threads. These threads all query the database to see if they have work to perform.

sessionFactory.getCurrentSession().createQuery("...").getResultList();

What happened We infrequently get:

AtomikosSQLException: Connection pool exhausted - try increasing 'maxPoolSize' and/or 'borrowConnectionTimeout' on the DataSourceBean.

What you expected to happen instead Some ideas

• Have Atomikos wait to grab a connection at a set interval with a maximum of borrowConnectionTimeout. This would mean replacing wait(remainderOfTime), with some wait(fractionOfRemainerOftime) here.

• Have Atomikos guarantee that the connection created in grow() is granted to the thread requesting a connection.

What TransactionsEssentials version you are using 6.0.109

Additional context Add any other context about the problem here.

[kyle-copeland]

Accidently opened issue before completing issue. Closing for now

[kyle-copeland]

Re-opening now that information is filled in

[GuyPardon]

Thanks for reporting this! Your first suggestion sounds feasible in the short term, the second one might be more involved?

[ponziani]

We're experiencing the same problem after upgrading from 3.8.0 to 5.0.9, I guess we will increase the minPoolSize for now, but we will also be looking forward to a fix.