Debounce & Throttle Rate-Limiting

Debounce and throttle are time-based rate-limiting operators that protect downstream resources from being overwhelmed by high-frequency upstream emissions. They model two distinct intentions: debounce waits for a quiet period before emitting the last value; throttle emits the first value in a time window and discards the rest. `debounceTime(300)` in RxJS waits 300 milliseconds after the last emission before forwarding it. This is the canonical operator for search-as-you-type: only the value 300ms after the user stops typing triggers an API call, collapsing dozens of keystrokes into one request. Angular's reactive form value changes piped through `debounceTime` is one of the most common patterns in production Angular applications. `throttleTime(1000)` emits the first value in each 1-second window and suppresses the rest. The use case is rate-limited event logging or scroll-position tracking: you want to know the position is changing, but not on every pixel. Kotlin Flow provides `debounce(timeoutMillis)` as a built-in operator that integrates with coroutine cancellation—the debounce delay is a `delay()` inside a `coroutineScope`, so it is cancellable and does not block threads. `sample(period)` emits the most recent value at a fixed interval, making it the Kotlin equivalent of `throttleTime` with `leading: false` semantics. The Reactive Manifesto's Responsive pillar—systems respond in a timely manner—is directly served by rate-limiting. Without debounce on user input, a Spring WebFlux backend receives one query per keystroke; at 200ms typing speed, a 10-character search generates 10 HTTP requests instead of 1. Uber's real-time driver-location update system uses sampling rather than streaming every GPS tick, reducing WebSocket message volume by orders of magnitude without degrading the user experience. Rate-limiting also appears in producer-side contexts: when an RxJS `interval` feeds a downstream service with a rate limit, `throttleTime` or `auditTime` enforces the budget without needing external coordination.