Tumbling vs sliding windows
A tumbling window closes and a new one starts, so each event lands in one window. A sliding window moves by a small step, so each event lands in many windows. With a 1-hour window and a 1-minute step, each call counts in 60 windows. At 40,000 calls/s, sliding windows fail 97 percent of requests.
2 workers · 1 TB moves in 1.1 h · 1,000 Mbps per card
Case 1
20,000 customers send 40,000 calls/s. Each call must be in exactly one hourly bill. The counter has 8 vCPU and 16 GB of RAM.
| Measure | Goal | Tumbling 1-hour windows | Sliding 1-hour, 1-minute step |
|---|---|---|---|
| p99 latency | under 200 ms | 2 ms Pass | 9.3 s Fail |
| Error rate | under 0.1% | 0% Pass | 96.8% Fail |
| Monthly cost | 64 USD/mo | 64 USD/mo |