speedscope fails to open Catapult files that don't all specify a pid

[alecazam]

We only use pid for the name of the profie.
None of our fields afterwards use it, and simply refer to a tid. This is to keep the json size down.

speedscope rejects these perfectly valid files. I'd like to move off Perfetto and over to speedscope. But I forget what issues that I had using it in the past. These files open fine in Perfetto.

Also when speedscope fails to parse these files, it produces no output in the console to help identify what went wrong or what line failed.

{
"displayTimeUnit": "ms",
"systemTraceEvents": "SystemTraceData",
"traceEvents": [

{
"name": "process_name",
"ph": "M",
"pid": 0,
"args": {
"name": "SkyPools.json"
}
},

{
"name": "thread_name",
"ph": "M",
"tid": 0,
"args": {
"name": "T0 b0 2"
}
},

{
"name": "TT-UiMapAtlas5",
"ph": "X",
"ts": 0,
"dur": 5593344,
"tid": 0,
"cat": "TT"
},

]
}

[alecazam]

This seems problematic in Chrome.ts, since tid and cat are not present in the first event.

if (!('pid' in first && 'tid' in first && 'ph' in first && 'cat' in first)) return false
if (
    !rawProfile.find(
      e => e.name === 'CpuProfile' || e.name === 'Profile' || e.name === 'ProfileChunk',
    )
  )
    return false

[jlfwong]

Hey Alec!

I'm not immediately familiar with the catapult format, but from inspection, it seems like it's probably the Chrome Trace format?

That's handled in trace-event.ts, not chrome.ts.

My guess is that it's failing import because of the detection here:

speedscope/src/import/trace-event.ts

Lines 762 to 771 in e5786f9

	function isTraceEventWithSamples(
	maybeTraceEventObject: any,
	): maybeTraceEventObject is TraceWithSamples {
	return (
	'traceEvents' in maybeTraceEventObject &&
	'stackFrames' in maybeTraceEventObject &&
	'samples' in maybeTraceEventObject &&
	isTraceEventList(maybeTraceEventObject['traceEvents'])
	)
	}

speedscope uses a series of heuristics to determine what format an imported file is. You can see those here: https://github.com/jlfwong/speedscope/blob/e5786f9b3e02e61032178e245f82f2620dc46333/src/import/index.ts

You can see instructions in https://github.com/jlfwong/speedscope/blob/main/CONTRIBUTING.md for how to set up locally to debug

[alecazam]

Hey Jamie, thanks for putting so much cool stuff into Speedscope! I'll check that file, and try feeding some traces into that. I need to host Speedscope in my tool kram-profile (currently hosts Perfetto).

[alecazam]

Also note that it's not enough to sortBy the starting timestamp. Since Catatpult doesn't store explicit hierarchy levels, they must be nested in the parent. But that means you can sort by startTime, and then on startTime ties by the duration.