Design Live Comments on a Broadcast · System Design Interview

Design Live Comments on a BroadcastDesign the comment stream running beside a live broadcast, where everyone watching writes into the same room.What it has to do

A viewer posts a comment and the room sees it within a second or two

Someone arriving midway sees what was said just before they joined

A viewer can be silenced, and their comments stop reaching the room

Scale

Viewers on the largest broadcast: 10 million

Comments per second in that room at peak: 50,000

Broadcasts running at once: 100,000

Out of scope

The video itself

Deciding automatically what counts as abuse

Gifts and paid highlights

Searching past comments

Practise this challengeAll system design challenges

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