rate limiting

Leaky Bucket

Requests fill a bucket that drains at a constant rate — smooths bursty traffic

Bucket Level0.00 / 8
Leak Rate1.2/s
Allowed0
Rejected0
bucket
↓ requests
1
2
3
4
5
6
7
8
max
·
empty
Fill Level
0.00 / 8 — draining at 1.2/s
output rate: 0 req/s (constant, regardless of input burst)
// events
No requests yet.

// how it works

Think of a bucket with a small hole at the bottom:

  • Requests add water to the bucket (level increases)
  • Water leaks out at a constant rate: elapsed × leakRate
  • If level + 1 > capacity → request rejected (overflow)
  • Output is always at a steady rate, smoothing bursts

// trade-offs

  • Smooths bursty traffic into steady output
  • O(1) time and space
  • Great for queue-based processing
  • No controlled bursting — rejects excess immediately
  • Can be too strict for bursty workloads