Re: bmake inefficiencies

["Simon J. Gerraty" <sjg%juniper.net@localhost>]

David Holland <dholland-current%netbsd.org@localhost> wrote:
> It might be necessary to try waiting a second time, because it might
> not be able to know how many children have exited (depends if they all

Yes, SIGCHLD tells you that at least one children died.
So looping on waitpid is needed.

> trigger some EOF or just most of them) but it should not need to
> blindly call waitpid every time through the main select/poll loop.

Indeed.
 
> Right now the SIGCHLD handler works by writing into a pipe that the
> main loop polls, which is pretty grotty. It shouldn't need to do
> anything other than set a global (of type sig_atomic_t, to be
> portable) to 1. The delivery of a signal should cause all select and
> poll variants to fail with EINTR (that is, stop for attention) even if
> nothing else is pending.

It now sets the flag thus the pipe may be superfluous.