Thread starvation
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
recognize and diagnose exhausted thread pools.
Planned topics
- Symptom: latency climbs while CPU stays low; requests queue.
- Causes: blocking calls on a small pool, a slow dependency holding threads, a pool used for both work and waiting (pool deadlock).
- Evidence: take thread dumps a few seconds apart; many threads waiting in the same call point to the culprit; check pool queue depth and active counts metrics.
- Fixes: timeouts, bulkheads (separate pools per dependency), bounded queues with load shedding, virtual threads for blocking I/O where suitable (verify version support and pinning issues).
Draft outline details
Demonstration
Thread dump excerpt: 200 http-nio-exec threads in WAITING inside a payment client read(). Interpretation: dependency slowness plus no timeout.
Check your understanding
CPU is low yet requests are slow. What do you suspect?
Show answer
Threads blocked waiting, such as pool exhaustion from a slow dependency.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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