$ancestors
is used only in the initialization stage, to get the parent's PID, which is used to catch the EXIT
message coming from the parent, so that the terminate
stuff can get executed. Erasing this key when the server is up and running makes no difference.
$initial_call
, on the other hand, is used in the crash report by proc_lib
to dump the MFA info.
A quick grep
in the OTP source tree can certainly help.