[mark_undoio]

Process recording by time travel debug seems like a good fit for this problem - then you can capture 100% of process execution and then go back and investigate further.

We (Undo.io) came up with a technique for following a tree of processes and initiating process recording based on a glob of program name. It's the `--record-on` flag in https://docs.undo.io/UsingTheLiveRecorderTool.html. You can grab a free trial from our website.

For open source, with rr (https://rr-project.org/) I think you'd just `rr record` the initial process and you'll end up capturing the whole process tree - then you can look at the one you're interested in.

As others have said you could also do some smart things with GDB's follow-fork settings but I think process recording is ideal for capturing complicated situations like this as you can go and review what happened later on.