Gnus stuck in select/gettimeofday loop

[Neil Woods]

I'm running the latest Gnu Emacs snapshot from Debian, and the latest
CVS snapshot of Gnus (checked out today).

Occasionally¹ Emacs will lock up completely whilst in Gnus, at this point
it is unresponsive to C-g. Doing an strace of the process gives the
following outputs:

% strace -Tvp 24093
[...]
select(8, [3 5 6 7], NULL, NULL, {0, 30}) = 0 (Timeout) <0.000640>
gettimeofday({1140846360, 622910}, NULL) = 0 <0.000016>
gettimeofday({1140846360, 623000}, NULL) = 0 <0.000017>
gettimeofday({1140846360, 623069}, NULL) = 0 <0.000016>
gettimeofday({1140846360, 623137}, NULL) = 0 <0.000015>
select(8, [3 5 6 7], NULL, NULL, {0, 31}) = 0 (Timeout) <0.000641>
gettimeofday({1140846360, 623910}, NULL) = 0 <0.000016>
gettimeofday({1140846360, 624019}, NULL) = 0 <0.000019>
gettimeofday({1140846360, 624089}, NULL) = 0 <0.000015>
gettimeofday({1140846360, 624157}, NULL) = 0 <0.000015>
[many repetitions of this...]

and strace for a few seconds:

% strace -c -p 24093
Process 24093 attached - interrupt to quit
Process 24093 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 98.76    7.385984         825      8952         1 select
  1.24    0.092740           3     35839           gettimeofday
  0.00    0.000035          35         1           write
  0.00    0.000012           6         2           read
  0.00    0.000005           2         3           ioctl
  0.00    0.000004           2         2         2 sigreturn
  0.00    0.000004           1         4           poll
------ ----------- ----------- --------- --------- ----------------
100.00    7.478784                 44803         3 total

There is a single network connection open from Emacs to sea.gmane.org,
which doesn't want to timeout - I suspect² this may be related.
Disconnecting from the net and waiting for 20 minutes had no effect.

Curiously, even though Emacs was unresponsive to the keyboard and mouse,
I *did* manage to exit Gnus by typing:

% gnuclient -q -f gnus-group-exit

At this point I saved buffers and exited.

Any help on this, and advice on how best I can debug this would be
greatly appreciated.

Thanks in advance. 

¹As I mentioned, this is an occasional occurrence (there is no way to
reproduce this on demand) - the above is the output of the last
occurrence a few minutes ago.

²Every time this has happened there has been an open network connection
which won't die, but stays in ESTABLISHED state, checked using netstat.

-- 
Neil.
Don't make a big deal out of everything; just deal with everything.