Threading concerns, concurrency, deadlocks?

Short answer: Avoid blocking calls in async code to prevent deadlocks. Use async/await properly. Protect shared data with locks or concurrent collections. Avoid thread starvation with thread pool tuning.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.