1559377 - Performance observer seems to be coupled to resource timing buffer

Status: RESOLVED WORKSFORME

(Core :: Performance: General, defect, P3)

Description

[bastien.caudan]

Attachment: example page

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36

Steps to reproduce:

Setup

• Create a PerformanceObserver on resource entries

Step 1

• Trigger 300 XHR requests

Step 2

• Trigger 300 XHR requests

Step 3

• Clear resource timings
• Trigger 300 XHR requests

Actual results:

Step 1: 250 performance entries reported
Step 2: 0 performance entry reported
Step 3: 250 performance entries reported

Expected results:

Step 1: 300 performance entries reported
Step 2: 300 performance entries reported
Step 3: 300 performance entries reported

Comment 1

[Raluca Popovici, Desktop QA]

Hi,
I was able to reproduce this issue on my machine (MacOS 10.14.5) with Firefox Release 67.0.3, Firefox Bet 68.0b9 and Niightly 69.0a1.

Thank you for your report.

Comment 2

[Daniel Holbert [:dholbert]]

Triaging as [qf-], since this doesn't seem to have much to do with responsiveness - just a correctness bug in this PerformanceObserver API.

Comment 3

[Benoît Zugmeyer]

FYI, this issue seems to be solved for a while. I bisected Firefox versions and it seems like Firefox 111.0 was the first version that reports all resources without needing to clear resources.

Comment 4

[Markus Stange [:mstange]]

Thanks for checking! Resolving this bug.