Cannot control thread order in perfetto

[bartosz-lew-int]

With the following trace event file:

{"traceEvents":[
{"name": "process_name", "ph": "M", "pid":0, "args": {"name" : "Process (0)"}},
{"name": "process_sort_index", "ph": "M", "pid":0, "args": {"sort_index" : "0"}},
{"name": "thread_name", "ph": "M", "pid":0, "tid":0, "args": {"name" : "th1"}},
{"name": "thread_name", "ph": "M", "pid":0, "tid":1, "args": {"name" : "th2"}},
{"name": "process_name", "ph": "M", "pid":1, "args": {"name" : "Process (1)"}},
{"name": "process_sort_index", "ph": "M", "pid":1, "args": {"sort_index" : "1"}},
{"name": "thread_name", "ph": "M", "pid":1, "tid":0, "args": {"name" : "th1"}},
{"name": "thread_name", "ph": "M", "pid":1, "tid":1, "args": {"name" : "th2"}},
{"name":"A", "cat":"X", "ph":"X", "ts":1, "dur":3, "pid":0, "tid":0},
{"name":"B", "cat":"Y", "ph":"X", "ts":2, "dur":2, "pid":0, "tid":1},
{"name":"A", "cat":"X", "ph":"X", "ts":1, "dur":3, "pid":1, "tid":0},
{"name":"B", "cat":"Y", "ph":"X", "ts":2, "dur":2, "pid":1, "tid":1}
]
}

one obtains the following report

where thread order in the first process follows thread id (or thread name lexicographic ordering) but the second process that contains exactly the same data shows threads in different order.

The expected result would be to have both threads in the same order.

using version: v35.0-8019b from
https://ui.perfetto.dev/

[LalitMaganti]

This is working as intended: we very intentionally do not support process_sort_index as we made a conscious choice to separate trace rendering from the trace contents. See also our policy on JSON traces here.

Improving options for visualising only the parts of the trace which matter to the user is something which is being worked on right now and is tracked by #429

[bartosz-lew-int]

Thanks for the answer and tips. However the main point was about having some rules that would help to understand the ordering in which threads are being displayed (not processes). I'd appreciate to know if there is some workaround for this to have the above threads presented in the report in the consistent order i.e.

process 0
th1
th2

process 1
th1 (rather than th2)
th2 (rather than th1)

Thanks again.
ps. Indeed the report looks fine in the Legacy UI.

[LalitMaganti]

I'd appreciate to know if there is some workaround for this to have the above threads presented in the report in the consistent order i.e.

There are no workarounds I'm afraid. The order of the tracks is determined by the "activity" of the process (think the amount of time that a slice is active across all the threads). This is hardcoded into the UI and there's no way to change this at the moment.