Timeouts

In this lesson you will

Distinguish the auction timeout, bidderTimeout, and failsafeTimeout.
Explain the revenue trade: too short starves bids, too long delays the ad-server call.
Understand that setTimeout is not a hard guarantee.

Set the timeout too short and you leave money on the table, slow bidders never answer. Too long and the page just sits there while the user scrolls away. The timeout is the single most-tuned number in header bidding.

Timeout	What it controls
bidderTimeout	The deadline for this auction. When it hits, Prebid stops waiting and proceeds with the bids it has.
failsafeTimeout	A hard backstop that sends the ad request even if Prebid never called back at all.
Auction timeout	In practice the same as bidderTimeout: the budget you give the whole auction.

Key idea

The trade: too short starves bids (less competition, lower CPM), too long delays the ad-server call (worse viewability and page experience). Most real setups land between 1000 and 2500ms.

Watch out

setTimeout is not a hard guarantee. A busy main thread can blow past it, which is exactly why failsafeTimeout exists: a separate backstop so the ad still requests even when the auction stalls.

Quick check

80% of bids arrive by 1200ms; the rest straggle in by 4000ms. Where would you set the timeout?

Note

The Prebid analyzer (and the Inspect tool) flag a bidderTimeout that is too low or too high on a real config.

Key concepts

bidderTimeoutfailsafeTimeoutThe latency-vs-bid-density trade

Going deeper

To really lock this in: given a latency histogram, choose a timeout that captures the 80th percentile without exceeding a page-experience budget.

Where this leads

DEBUG

Proposed timeout-tuning sandbox.

PRACTICE

Proposed failsafe proof.

ANALYZE

See how the Prebid analyzer flags a too-low or too-high bidderTimeout on a real config.

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