Comment 8 for bug 185601

It looks like the only solution is to use a SIGCHLD signal handler. Not
to "test" (sorry) but to be notified when a specific process has died.
An idea: register a procedure for a child and have that procedure called
when the SIGCHLD telling of that child's death is delivered to the
signal handler (you'd use SA_SIGINFO with sa_sigaction to install a
signal handler that would be given a siginfo_t telling what child PID
died); without screwing up ikarus's stack or run-time of course. Using
an alternate signal stack (via sigaltstack and SA_ONSTACK) might be
noteworthy. Ah, it looks like ikarus already does use sa_sigaction and
an alternate stack for SIGINT, but the handler doesn't call back into
Scheme.

Would this also be possible: If the callback procedure returns, the
continuation of the program from where it was at when the signal handler
was called is resumed, but the callback procedure could possibly not
return as its way of dealing with the death (hahaha).