LEARN. PRACTICE. GROW.Concept and mechanism
A data source should match the JNDI binding expected by the application and be available in the correct scope. The console display name does not replace that binding. After resolution, the pool manages connections with local limits: four JVMs with a maximum of thirty can represent one hundred and twenty connections, alongside other database consumers. The maximum is potential capacity rather than permanent utilization. In a dump, createOrWaitForConnection can indicate acquisition waiting; socketRead0 within JDBC indicates a read phase in an already started call. Interpret both alongside pool metrics, transaction duration, and database and network evidence. Increasing the pool before understanding the dependency can multiply pressure on a slow backend.
Guided application
A shareable connection can remain associated with a managed transaction after close closes the logical handle. If the same flow waits for a remote service before ending the transaction, it can extend retention without proving a leak. During a fictional daily close, correlate SQL blocking, threads, queue, and cutoff with the involved teams. Consider approved load containment rather than impulsively increasing concurrency. After failover, connections can become stale; pool recovery policy does not resolve the business outcome of a write with an unknown commit. Use references and reconciliation before retrying financial operations, with application-defined idempotency. Communicate what is established and what remains uncertain.
Full pools and blocked SQL call for joint investigation; more connections do not prove more capacity.
Common pitfalls
Confusing name with JNDI; treating the maximum as global; classifying retention as a leak; retrying unknown commits.
Related topics: ND topology and effective configuration · Deployment, routing, and state · JVM, logs, and time-based diagnosis
Locate the waiting phase and preserve consistency of effects.
Reference: Connection acquisition waits and held transactions · DR WebSphere traditional ND 9.0.5; maintenance baseline 9.0.5.29 (2026-09-08); documentation reviewed 2026-09-30