bug#9291: 23.3.50; Emacs takes long time to start up due to DNS

bug#9291: 23.3.50; Emacs takes long time to start up due to DNS

[Leo]

On my machine, emacs -q -nw normally takes 0.1 seconds. But I have just
found that it could take more than 10 seconds on some network. I have
this device that provides wifi/wapi through the telencom network here,
so the behaviour is readily reproducible. Let me know how I may provide
more information for debugging. AFAICT this happens in 24.0.50 too.

I am running emacs 23.3.50 on OSX 10.6.8.

leo@bogon ~$ time emacs -q -nw

real	0m11.347s
user	0m0.207s
sys	0m0.037s

Backtrace in GDB reveals this:

#0  0x00007fff85677c0a in kevent ()
#1  0x00007fff856b69fa in _mdns_query_mDNSResponder ()
#2  0x00007fff856b5db7 in _mdns_search ()
#3  0x00007fff856b4ffc in _mdns_addrinfo ()
#4  0x00007fff856b4059 in search_addrinfo ()
#5  0x00007fff856b3a7a in si_addrinfo ()
#6  0x00007fff856b348d in getaddrinfo ()
#7  0x000000010012915e in init_system_name () at sysdep.c:1793
#8  0x00000001001a4b9d in init_editfns () at editfns.c:154
#9  0x00000001001021bc in main (argc=3, argv=0x7fff5fbff5f8) at emacs.c:1768

BTW, is it possible for init_system_name to be done async?

Leo

bug#9291: 23.3.50; Emacs takes long time to start up due to DNS

[Stefan Monnier]

> On my machine, emacs -q -nw normally takes 0.1 seconds. But I have just
> found that it could take more than 10 seconds on some network. I have
> this device that provides wifi/wapi through the telencom network here,
> so the behaviour is readily reproducible. Let me know how I may provide
> more information for debugging. AFAICT this happens in 24.0.50 too.

I think you'll find an answer in etc/PROBLEMS:

*** Emacs startup on GNU/Linux systems (and possibly other systems) is slow.

This can happen if the system is misconfigured and Emacs can't get the
full qualified domain name, FQDN.  You should have your FQDN in the
/etc/hosts file, something like this:

127.0.0.1	localhost
129.187.137.82	nuc04.t30.physik.tu-muenchen.de	nuc04

> BTW, is it possible for init_system_name to be done async?

Could be.


        Stefan