Bug 168055 - [Navigation Timing] requestStart, responseStart before navigationStart
Summary: [Navigation Timing] requestStart, responseStart before navigationStart
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Platform (show other bugs)
Version: Safari 10
Hardware: All All
: P2 Normal
Assignee: Nobody
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-02-09 10:34 PST by Nic Jansma
Modified: 2017-02-10 15:18 PST (History)
3 users (show)

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Description Nic Jansma 2017-02-09 10:34:27 PST
Hi,

We're seeing infrequent cases where NavigationTiming timestamps such as requestStart and responseStart are happening prior to navigationStart.

Here's one example:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/602.2.14 (KHTML, like Gecko) Version/10.0.1 Safari/602.2.14

navigation.type             0             // navigation
redirectStart               0
redirectEnd                 0
requestStart                1486654516288 // incorrect: before navigationStart
responseStart               1486654516819 // incorrect: before navigationStart
navigationStart             1486654517415
fetchStart                  1486654517415
domainLookupStart           1486654517415
domainLookupEnd             1486654517415
connectStart                1486654517415
connectEnd                  1486654517415
domLoading                  1486654518045
responseEnd                 1486654518085
domInteractive              1486654518312
domContentLoadedEventStart  1486654518312
domContentLoadedEventEnd    1486654518316
domComplete                 1486654518596
loadEventStart              1486654518599

Here's a second example:

Mozilla/5.0 (iPhone; CPU iPhone OS 10_2_1 like Mac OS X) AppleWebKit/602.4.6 (KHTML, like Gecko) Version/10.0 Mobile/14D27 Safari/602.1

navigation.type             0             // navigation
redirectStart               0
redirectEnd                 0
requestStart                1486647959659 // incorrect: before navigationStart
navigationStart             1486647959737
fetchStart                  1486647959737
domainLookupStart           1486647959737
domainLookupEnd             1486647959737
connectStart                1486647959737
connectEnd                  1486647959737
responseStart               1486647959828
responseEnd                 1486647959969
domLoading                  1486647959971
domInteractive              1486647962594
domContentLoadedEventStart  1486647962710
domContentLoadedEventEnd    1486647962985
domComplete                 1486647967189
loadEventStart              1486647967192

This doesn't happen frequently -- in one data set I'm looking at, it's 3 beacons out of 254,357.