Principle
Push back on intake before the backlog becomes the outage
A growing queue is a message from capacity, not a storage success story.
When it fits
- Work arrives faster than it can be completed and producers keep submitting at the same rate.
When to avoid it
- Backpressure needs clear user behavior; invisible throttling can look like random failure.
Why it matters
When consumers approach their sustainable limit, slow or reject new intake rather than allowing unbounded backlog growth. Propagate the pressure to the producer through quotas, concurrency limits, retry-after signals or explicit scheduling. The producer must see that capacity is constrained.
An example
Limit new agent jobs when human review capacity is saturated instead of generating thousands of outputs that will expire unread.
Check your result
Backlog pressure changes intake behavior before the system exhausts memory, deadlines or reviewer capacity.
Keep this limit in mind
- Backpressure needs clear user behavior; invisible throttling can look like random failure.
Connected ideas
Useful withGive shared capacity a noisy-neighbor rule
Evidence and sources
AWS's 2026 fairness guidance uses throttling, quotas and backpressure to prevent one workload from starving others in a shared system.
Fairness policy must reflect actual priorities rather than equalizing workloads that have different importance.
Fairness in multi-tenant systems · Admission control and fairness
Google SRE recommends small queues or early rejection under steady overload because long queues add latency, memory use and work that may already have missed its deadline.
Bursty asynchronous workloads can legitimately benefit from larger queues when backlog remains useful.
Addressing Cascading Failures · Queue management and latency/deadlines