Message 139135 - Python tracker

> since all the processes receive the signal at the same time,
> their outputs will be interleaved (we could maybe add a random
> sleep before dumping the traceback?)

And we have the pid list of the children, we can use an arbitrary sleep (e.g. 1 second) before sending a signal to the next pid. Anyway, a sleep is the most reliable synchronization code after a crash/timeout.