Re: [9fans] wait hang

["Russ Cox" <rsc@swtch.com>]

You're right again.  The "wait" command will work correctly --
it won't return until all children have finished.  What might not
work is waiting for a particular pid.  That is, if you do something like

sleep 1000000 &
pids=()
for(i in `{seq 200}){
  echo foo >/dev/null &
  pids=($pids $apid)
}
for(p in $pids)
  wait $p

then since the kernel tosses away some of the wait records,
the first wait $p for a tossed-away record will just loop calling
wait and never getting the expected record.  It will not give up
because there is still the one child (sleep 1000000) left.

I'm not really convinced this part of rc ever worked right to
begin with, so this is no big loss.

Plain "wait", with no argument, does work correctly now.

Russ