[Sbcl-devel] stumpwm hangs

[Julian S. <der...@we...>]

Hello,

stumpwm (http://www.nongnu.org/stumpwm/) tends to hang now and then
(once in a day or two) when running external programs from its X event loop
via run-program. In my particular case, I call iwconfig to display
wireless networking info in stumpwm's mode-line.

Because of this I run stumpwm inside a screen session. Hitting ^C in the
terminal gives the following backtrace:

debugger invoked on a SB-SYS:INTERACTIVE-INTERRUPT in thread #<THREAD "initial thread" RUNNING {B225671}>:
  Interactive interrupt at #xB7FE3424.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [CONTINUE    ] Return from SB-UNIX:SIGINT.
  1: [QUIT-STUMPWM] Quit Stumpwm

("bogus stack frame")
0] backtrace

0: ("bogus stack frame")
1: (SB-SYS:DECODE-TIMEOUT 0)
2: (SB-SYS:SERVE-EVENT 0)
3: (SB-SYS:SERVE-ALL-EVENTS 1)
4: (SB-EXT:PROCESS-WAIT #<SB-IMPL::PROCESS :EXITED 0> NIL)
5: (SB-EXT:RUN-PROGRAM "/bin/sh" ("-c" "/sbin/iwconfig wlan0 2>/dev/null"))[:EXTERNAL]
6: (STUMPWM::RUN-PROG-COLLECT-OUTPUT "/bin/sh")[:EXTERNAL]
7: (RUN-SHELL-COMMAND "/sbin/iwconfig wlan0 2>/dev/null" T)
8: (STUMPWM.CONTRIB.WIFI::FMT-WIFI #<unavailable argument>)
9: (STUMPWM::FORMAT-EXPAND
    ((#\I #) (#\B #) (#\t STUMPWM::FMT-CPU-TEMP) (#\f STUMPWM::FMT-CPU-FREQ)
     (#\C STUMPWM::FMT-CPU-USAGE-BAR) (#\c STUMPWM::FMT-CPU-USAGE)
     (#\w STUMPWM::FMT-WINDOW-LIST) (#\g STUMPWM::FMT-GROUP-LIST)
     (#\h STUMPWM::FMT-HEAD) (#\n STUMPWM::FMT-GROUP)
     (#\W STUMPWM::FMT-HEAD-WINDOW-LIST) (#\u STUMPWM::FMT-URGENT-WINDOW-LIST))
    "%c %f@%t | BAT %B | %I | %g
%W")[:EXTERNAL]
10: (STUMPWM::REDRAW-MODE-LINE
     #S(STUMPWM::MODE-LINE
        :SCREEN #S<screen #<XLIB:SCREEN :0.0 1440x900x24 TRUE-COLOR>>
        :HEAD #S(frame 0 NIL 0 0 1440 900)
        :WINDOW #<XLIB:WINDOW :0 A0000C>
        :FORMAT *SCREEN-MODE-LINE-FORMAT*
        :POSITION :TOP
        :CONTENTS "CPU: ^[ 12%^]  1.00GHz@58 C | BAT ~ 100% | boelthorn ^[97%^] | 1-im ^R2*web^r 3+emacs 4-irc 5-music
^R 0*Typemaps - Minefield^r"
        :CC #S(STUMPWM::CCONTEXT
               :WIN #<XLIB:WINDOW :0 A0000C>
               :GC #<XLIB:GCONTEXT :0 10485773>
               :DEFAULT-FG 8355711
               :DEFAULT-BRIGHT 12566463
               :DEFAULT-BG 0)
        :HEIGHT 32
        :FACTOR 217/225
        :MODE :STUMP)
     NIL)
11: (STUMPWM::UPDATE-MODE-LINES
     #S<screen #<XLIB:SCREEN :0.0 1440x900x24 TRUE-COLOR>>)
12: (STUMPWM::UPDATE-ALL-MODE-LINES)
13: (STUMPWM::RUN-EXPIRED-TIMERS
     (#S(STUMPWM::TIMER
         :TIME 13159444
         :REPEAT 5
         :FUNCTION STUMPWM::UPDATE-ALL-MODE-LINES
         :ARGS NIL)))
14: (STUMPWM::STUMPWM-INTERNAL-LOOP)
15: (STUMPWM::STUMPWM-INTERNAL-LOOP)[:EXTERNAL]
16: (STUMPWM::STUMPWM-INTERNAL ":0.0")
17: (STUMPWM ":0.0")
18: ((LAMBDA ()))
19: ((LABELS SB-IMPL::RESTART-LISP))

Another time I got:

0: ((FLET #:CLEANUP-FUN-[SELECT-DESCRIPTOR-HANDLERS]74))[:CLEANUP]
1: (SB-IMPL::SELECT-DESCRIPTOR-HANDLERS #<CLOSURE (LAMBDA #) {C177F0D}>)
2: (SB-IMPL::SELECT-DESCRIPTOR-HANDLERS #<CLOSURE (LAMBDA #) {C177F0D}>)[:EXTERNAL]
3: (SB-IMPL::SUB-SUB-SERVE-EVENT 0 0)
4: (SB-IMPL::SUB-SERVE-EVENT 0 0 NIL)
5: (SB-SYS:SERVE-ALL-EVENTS 1)
6: (SB-EXT:PROCESS-WAIT #<SB-IMPL::PROCESS :EXITED 0> NIL)
7: (SB-EXT:RUN-PROGRAM "/bin/sh" ("-c" "/sbin/iwconfig wlan0 2>/dev/null"))[:EXTERNAL]
...


I have failed to produce a small testcase to provoke this hang, which
has so far crippled every attempt at debugging this. If I can supply
additional info in order to resolve this, I am more than happy to do
this. This is a 

My system:
SBCL 1.0.19-gentoo
Linux 2.6.27 (Gentoo)
x86 dual core

Regards,
-- 
Julian Stecklina

Well, take it from an old hand: the only reason it would be easier to
program in C is that you can't easily express complex problems in C,
so you don't. - Erik Naggum (in comp.lang.lisp)