how to create a parent track to nest multiple tracks

[shuangshxing]

I want to create a parent track which nests multiple processes, and find a related discussion #914 ,which mentioned that we can create a tree of track to visualize logs hierarchically. I have a try, but the parent track couldn't be visualized by UI, only process and thread could be visualized.
Here I take a simple tree of track as example, and the packets in text format like below:
parent track(name:'mo*', uuid:10000)
->process(pid:1003, process_name: xxxx), parent_uuid:10000, uuid: 1003
->thread_1(pid:1003, tid: 8, thread_name: xxx), parent_uuid:1003
->thread_2(pid:1003, tid: 9, thread_name: xxx), parent_uuid:1003

anyone can help found the cause of the issue? and how to resolve?

[aMayzner]

Hi! It doesn't work because the process/thread hierarchy is making the parent/child hierarchy obsolete. You need to ditch the process/thread if you want arbitrary nesting.

Read https://perfetto.dev/docs/getting-started/converting#grouping-tracks-with-hierarchies for details on how to group the tracks and https://perfetto.dev/docs/reference/synthetic-track-event for more information on synthetic trace generation.