What is chunked prefill, and how does it stop long prompts from stalling decode?
One long prompt can freeze every other user's token stream for hundreds of milliseconds. Chunked prefill carves that prompt up so decode keeps flowing. Here is the mechanism and the knob that controls it.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
One long prompt can freeze every other user's token stream for hundreds of milliseconds. Chunked prefill carves that prompt up so decode keeps flowing. Here is the mechanism and the knob that controls it.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
