Re: busyloop in sigchld_handler

[Sam Steingold <sds@gnu.org>]

Andreas Schwab wrote:
> Sam Steingold <sds@gnu.org> writes:
> 
>> wait3 is a system call, which, when invoked in a loop, prevents the
>> kernel from doing anything else (in this case, sending SIGCHLD to
>> emacs). sleep allows the kernel some time to pass the signal.
> 
> I don't find this explanation convincing at all.  Since the system call is
> made _inside_ the signal handler, the signal is actually blocked here, so
> it cannot be delivered anyway.

yes, you are right.
what I should have said was that by making a system call in a busyloop, 
emacs prevents the kernel from doing what it needs to do to the the 
child so that wait3 will succeed.

Sam.