Debugging child processes, -f versus -p versus -g

Benjamin Smedberg benjamin at
Wed Apr 6 16:55:20 UTC 2016

I am trying to debug some Firefox plugin tests which have a process 
hierarchy, and I don't quite understand how debugging multiple processes 
in a recording works, and in particular -f and -p.

First: when you're debugging a replay, do you have access to all the 
processes in one debugging session? Or is it necessary to debug one 
process at a time and then use event-numbers to synchronize? If they are 
all one debugging session, do breakpoints apply to all processes or just 

Second: what processes do -p and -f attach to by default? Is the primary 
difference between them that -f <PID> attaches to the "parent" of PID -p 
attaches to the child of PID, but at the same point in time? Or am I 
totally misunderstanding?


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