How to print all coroutines' stack trace?

[choleraehyq]

Using gdb or something else. It's quite important for debugging.

[Xudong-Huang]

how to print the backtrace of one coroutine that is suspending? We could get all the registers context of a coroutine through the coroutine handle. But how to use it to print all the traceback is still unclear. I think We need to develop special tools or scirpts for gdb, which I have little experience on it.