How failures cascade
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
see how one slow dependency takes down callers.
Planned topics
- A slow service is worse than a dead one: callers wait, threads pile up, and pools fill.
- Little's law: concurrent requests = arrival rate × latency; latency rising 10× means 10× threads held.
- Once the caller's pool is full it fails for every endpoint, even those not using the slow dependency.
- Retries multiply load on the struggling service (retry storm).
- Defenses: timeouts, bounded retries, circuit breakers, bulkheads, fallbacks.
Draft outline details
Demonstration
diagram: checkout → payments (slow). Thread pool of 200 fills with waiting calls; GET /products also stalls.
Check your understanding
Why can a slow dependency break unrelated endpoints?
Show answer
Shared threads or connections are all held by waiting calls.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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