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Capture repeated thread dumps with jcmd or jstack while the incident is active. A deadlock cycle shows threads waiting for locks held by each other; distinguish it from starvation or a slow dependency by checking whether owners can progress. Fix consistent lock order, shorten critical sections, or redesign ownership so both locks are not required together.

A deadlock detector aborts one transaction so another can progress. Capture lock and query evidence, then retry the whole business transaction only if its effects are safe to repeat. Use bounded attempts with jitter, consistent resource ordering, and idempotency for any external side effects.

If every worker submits a task to the same bounded executor and synchronously waits for that task, no worker remains to run queued children. This is thread-pool starvation, not necessarily a monitor deadlock. Avoid blocking composition on the same pool, separate workloads, or use asynchronous completion and bounded concurrency.

Thread pools reuse worker threads. A ThreadLocal value can remain attached after a request ends, retaining large objects or exposing one request’s context to a later task if it is not overwritten. Clear it in a finally block or use a scoped context mechanism with well-defined propagation and cleanup.