Cannot import this Chrome profile: "TypeError: undefined has no properties"

[mstange]

I captured this profile in Chrome Canary:

Version 109.0.5396.0 (Official Build) canary (arm64)

When I drag it into profiler.firefox.com, I get the following:

Firefox Profiler

Couldn’t read the file or parse the profile in it.

TypeError: undefined has no properties

The full stack has been written to the Web Console.
Back to home

[julienw]

In this profile, we get this in the args.data object:

{
  "endTime": 1592522258792
}

instead of the more usual:

{
  "cpuProfile": {
    "nodes": [ /* ... */ ],
    "samples": [ /* ... */ ]
  },
  "lines": [ /* ... */ ],
  "timeDeltas": [ /* ... */ ]
}

I'm not sure yet what this means. I can't find endTime in the 2 sources of documentation I have [1] [2].

[1] https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview
[2] https://source.chromium.org/chromium/chromium/src/+/main:base/trace_event/trace_event.h;l=1

I suppose we could ignore these events so that we can at least import the profile:

profiler/src/profile-logic/import/chrome.js

Lines 535 to 536 in b5f7ff5

	const { cpuProfile } = profileChunk.args.data;
	const { nodes, samples } = cpuProfile;

[canova]

This is the type of even we expect in our importer:
https://source.chromium.org/chromium/chromium/src/+/main:v8/src/profiler/profile-generator.cc;l=690-747;drc=69ad9552b28299558b52eb002daf949b8f9e8bbc

Looks like this unexpected event is coming from this code here:
https://source.chromium.org/chromium/chromium/src/+/main:v8/src/profiler/profile-generator.cc;l=755-764;drc=69ad9552b28299558b52eb002daf949b8f9e8bbc

The comment above explains that this endTime is added for backwards compatibility. Probably it should be okay to ignore it?

[julienw]

Ah, good findings! Then yes I guess we can just ignore it