zombie windows processes - cygwin 1.5.23-2

[Mark Fisher]

recently with the updates to the handling of zombies, i'm actually
seeing more of them using cygwin 1.5.23-2.

[after writing this lengthy report, i thought i'd try out the latest
snapshot dll and the problems all completely disappear. i cannot
produce zombies using cygwin1-20061218.dll.bz2]

the problems all seem to manifest through starting apps under X, hence
i'm cross posting this to cygwin-xfree.

in this environment, i can quite easily produce windows zombies (i.e.
show under windows task manager, but not under cygwin ps) almost any x
app: gnuplot, rxvtc-X, emacs, xset, wmbgset. but it isn't consistent,
it's quite random in happening.

for instance, i just ran multiple times "xset q" and on the 6th
attempt, it hung (all the output is there, it just doesn't come back
to the console, and from another shell, i see the xset process has no
parent process id), where i now have to kill the windows process at
which point, my prompt then reappears.

i've minimized my .xinitrc to only start up urxvtd, and a single
client with "LC_CTYPE=en_UK.UTF-8 urxvtc -e /bin/bash --login"
and no window manager, or any other application running.

if i do ps -ef i get:
     UID     PID    PPID TTY     STIME COMMAND
   markf   20676       1 con  14:03:54 /usr/bin/rxvt
   markf   20768   20676   2  14:03:54 /usr/bin/bash
   markf   19064       1 con  14:06:56 /usr/bin/rxvt
   markf   19376   19064   0  14:06:56 /usr/bin/bash
   markf   22096       1   0  14:08:40 /usr/X11R6/bin/xinit
   markf   20648   22096   0  14:08:40 /usr/X11R6/bin/XWin
   markf   18448   22096   0  14:08:42 /usr/bin/bash
   markf   17380   18448   0  14:08:42 /usr/bin/urxvtd-X
   markf   21916   17380   1  14:08:43 /usr/bin/bash
   markf   22268   21916   1  14:10:40 /usr/bin/ps


but there is a zombie process you can see under ps -W:
      PID    PPID    PGID     WINPID  TTY  UID    STIME COMMAND
    20304       0       0      20304    ?    0 14:08:43
C:\cygwin\bin\urxvtc-X.exe

also, after creating zombies through emacs/gnuplot, i also see:
    20712       0       0      20712    ?    0 14:15:34 C:\cygwin\bin\emacs.exe
    22340       0       0      22340    ?    0 14:01:52
C:\cygwin\usr\sbin\gnuplot\4.0\gnuplot_x11.exe

this is how all the zombies appear, no PPID, no PGID and not viewable
under ps -ef.

gnuplot (the one started from any rxvt session) correctly runs and
closes, but if i get it to display any graphs, it leaves a gnuplot-X11
process around that i have to kill under task manager (which seems to
be the spawned process for the graph). i close the graph with "q" to
quit it, or with the X close button, both lead to same result.

emacs cannot decide between working (70%), working but then creating a
zombie, or just throwing this error when i start:
      3 [sig] emacs 20972 C:\cygwin\bin\emacs.exe: *** fatal error -
called with threadlist_ix -1

the only error i've seen is the emacs one here, all the others just
hang until i kill them, unfortunately this is causing my normal
".xinitrc" to sometimes not get to the window manager (because of
calling xset 3 times that i then have to manually kill).

i can live with this for now as i can work around it [and now see that
the snapshot dll is ok], but i did want the list to know that things
have definitely gone "freaky" over the last couple of cygwin releases
for me.

i've been able to reproduce the zombies by replacing rxvt with xterm
(and still no window manager).

mark
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