Relaxed
Servers idle often.
The single idea
Arrivals meet capacity. The gap is your queue.
When λ < c·μ the system drains.
Healthy
Queue forms and clears.
Fragile
Small spikes cause large delays.
Unstable
Queue grows without bound.
Interactive
Flow Lab
Tune the sliders.
arrival
queued
serving
dropped
—
now / max 0
moving average
served items
capacity overflow
What you should see
Six situations, one model
Click each preset above.
Idle
λ ≪ μ.
Steady
ρ ≈ 0.8.
Fragile
ρ ≈ 0.95.
Overload
λ > c·μ.
Bursty
High CV².
Multi-server
Same λ, more servers.
Cross-domain transfer
Same law — different context
After the lab, map the model to your stack.
API queue
Requests wait for workers.
Test stand queue
Boards queue for ICT/FCT.
Event queue
ISR enqueues faster than main loop drains.
Backpressure
Pipeline stall when downstream is slow.
Self-check