reliabilitystreamingload-managementlatency
Backpressure
Control producer rate based on downstream capacity to avoid queue explosions and cascading failures.
Definition
Backpressure mechanisms slow, shed, or buffer incoming work when consumers cannot keep up.
When To Use
- Streaming pipelines with bursty ingress and bounded consumer capacity.
- Realtime systems where queue growth directly affects user latency.
- Any multi-stage architecture with potential stage imbalance.
When Not To Use
- Tiny systems with constant low utilization and no burst risk.
- Without clear overload policy (drop, delay, degrade).
- When producer throttling cannot be enforced by protocol.
Tradeoffs
- Prevents collapse under load, but may reject or delay user requests.
- Stabilizes latency, while reducing peak throughput temporarily.
- Improves reliability, with complexity in signaling across service boundaries.
Common Failure Modes
- Missing backpressure causes unbounded queue growth and OOM.
- Over-aggressive throttling underutilizes healthy capacity.
- No prioritization starves critical traffic during overload.
Interview Framing
Use this structure when the interviewer asks for this pattern explicitly.
Describe overload policy tiers, queue depth SLOs, and how producers learn downstream saturation.
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