Back to roadmap
Module 9 · Protocols, Security, ObservabilityDay 08320 min

Polling, Long Polling, and Push Models

Climb the realtime ladder by problem, not preference.

← PreviousNext →
Day 083

Polling, Long Polling, and Push Models

Short poll
note
Long poll
note
Push
note
Memory hook

Polling, Long Polling, and Push Models: climb the realtime ladder by problem, not preference

Mental model

design for the day something breaks

Design lens

Long poll keeps connections held; LB capacity matters.

Recall anchors
Short pollLong pollPush (WS/SSE)

Why it matters

Short polling repeatedly hits the server. Long polling holds a request open until data is ready. Push (WebSocket/SSE) opens a stream. Each is right for a band of update frequency and latency need.

Deep dive

<1 update/min: short poll is fine.

1–60 updates/min: long polling or SSE balances cost.

>1/sec: WebSocket or persistent stream.

Demo / scenario

Notification feed: ~10 updates/hour per user.

  1. Short poll every 30s? Wasteful at 10M users.
  2. Long poll: server holds connection up to 60s.
  3. Server replies on event; client immediately reconnects.
  4. Cheaper than continuous push for moderate frequency.

Tradeoffs

  • Long poll keeps connections held; LB capacity matters.
  • Push minimizes latency but costs sessions.
  • Short poll is easiest to debug.

Diagram

Short poll
Long poll
Push
Polling models.

Mind map

Check yourself

Loading quiz…

Sources & further reading

← PreviousNext →