How to get the flame graph of a process running in a container

[pkking]

I have a openresty process running in a docker container.
My work steps:

1. Run sample-bt-off-cpu -t 5 -p 4690 -u/-k on the host
2. Run ./stackcollapse.pl offcpu1.bt |./flamegraph.pl > sample-bt-off-cpu.svg
   Results:
3. A perfect kernel space flame graph
4. A unusual user space flame graph like this
   

MY QUESTION is, can this toolkit work with container or what i missed?

[agentzh]

@pkking AFAIK, containers are always problematic when running systemtap tools. It needs a lot of work to get it right, if not impossible. One common mistake is not giving your container enough permissions. Well, I cannot be more helpful here.