| Concern | sync.Pool | Blocking Pool |
|---|---|---|
| Upper bound on objects | ❌ None | ✅ Enforced |
| Behavior under load | Create more | Apply backpressure |
| Failure mode | External system overload | Callers block |
| GC influence | High | None |
| Intended domain | Cheap, ephemeral values | Scarce external resources |