Intent to Prototype: Remove Prefetch 5-minute Rule
Noam Rosenthal
Contact emails
nrose...@chromium.orgExplainer
NoneSpecification
https://github.com/whatwg/html/pull/8111Summary
Currently when a resource is prefetched using <link rel=prefetch>, we ignore its cache semantics (namely max-age & no-cache) for the first use within 5 minutes, to avoid refetching. Proposing to remove this behavior and use standard HTTP cache semantics.
Blink component
Blink>LoaderMotivation
The 5-minute rule was never standardized, not implemented by other browsers, and now as part of an effort to make prefetch interoperable across browsers I would like to align on a behavior that doesn't include this. Data to support this: 1. A UMA histogram shows that 0.05% of prefetch reuses actually benefit from this. About 85% of prefetches are reused regardless (e.g. inside the max-age anyway), and about 15% are not reused (e.g. 5 minutes have passed, not the first reuse). 2. Developers who rely on this can opt-in to this behavior, by setting a 5-minute max-age on prefetch requests (requests with a [Sec-]Purpose: prefetch header). Spec PR to align on prefetch processing: https://github.com/whatwg/html/pull/8111 Chromium Bug for the removal: https://bugs.chromium.org/p/chromium/issues/detail?id=1345207
Initial public proposal
TAG review
TAG review status
Not applicableRisks
Interoperability and Compatibility
Gecko: Already not implementing this
WebKit: Positive on aligning on prefetch
Web developers: very low usage of this feature, as shown by UMA
Other signals:
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
Debuggability
Is this feature fully tested by web-platform-tests?
NoFlag name
Requires code in //chrome?
FalseEstimated milestones
No milestones specified