We made some experimentations with Chrome network throttling and auctionConfig timeouts and it seems that with slow network connections like 3G there are cases where we are never able to actually load the bidding script. The auction just times out with the following error and the network request is left of pending.

Worklet error: https://fledge.us.preprod.criteo.com/simplebid?.. perBuyerCumulativeTimeout exceeded during bid generation.

config:

• bidding script size 100 KB, using HEADER cache-control: private, max-age=180
• network throttling 3G
• perBuyerTimeouts 50ms
• perBuyerCumulativeTimeouts 2sec

When using HTTP caching it is our expectation that the bidding script would just continue downloading and be available from cache for the next auction (as loading the script from cache would be significantly faster on devices with slow network connections, going down from seconds to ms)

I attaching the export logs and Chrome traces for 2 successive auctions done on some test pages with a real bidding script.

It looks related to issue #1347 but might not be the only reason for this behavior mentioned there.

chrome-net-export-log.json
trace_aborted_biddingscipt_download.json.gz