Help! -- Creeping Error location.

[William S. Shu]

I have a memory error (seg-fault) whose location changes from run to run, thus
I cannot set any watchpoints.  Even when I do set a break point on a previously
identified location, more or less grinds to a halt.  I cannot even kill it (I
suspect tis last is complements of Windows98). I have not used the "vary seed"
start-up option and so expect random no. generation from the same seed from run
to run (as usual default).

Question 1) has anyone else come across such strange behaviour?  My experience
with debuggers is that runs are repeatable!

The problem is linked with dropping objects for which I have scheduled
(separately) a behaviour using a separate, controller swarm. I use
addref:withArgument: to detect when an object is being dropped, and so call a
function notifyDrop(x,y,z) to terminate the scheduled behaviour (and drop its
schedule & activity).  The controller swarm it self is put on a list from
whence it is later dropped.  (I assume dropping the controller drops its own
schedules/activities and any schedules/activities under it --  just in case I
missed dropping any, somehow)

The above worked well when tested.  Then, I started tidying up other parts of
the program ... .  The only new or "strange" thing I did in the tidy-up is to
create class methods:
            // create probes for selected variables and store in probeMap
            + (id) makeVarProbes: (id <ProbeMap>) probeMap;

            // create probes for selected Messages and store in probeMap
            + (id) makeMessageProbes: (id <ProbeMap>) probeMap;
which simply factor out multiple occurrences of the same code.

Question 2) What could be wrong?  Was the scheduling code initially working on
a spurious basis?


I am using Swarm 1.4.1, and Gdb 4.17 under windows 98

a sample debugger output follows.

Thanks william.


--- [debugger code:
Current directory is c:/u/mosq/proto/
GNU gdb 4.17.1
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i586-cygwin32"...
(gdb) run
Starting program: /u/mosq/proto/persons.exe
7fce0000:/WINDOWS/SYSTEM/SHELL32.DLL
bfc00000:/WINDOWS/SYSTEM/COMCTL32.DLL
bfb50000:/WINDOWS/SYSTEM/SHLWAPI.DLL

[failed reading symbols from DLL]
"/WINDOWS/SYSTEM/COMDLG32.DLL": error reading line numbers

66300000:/SWARM-1.4.1/BIN/CYGTK80.DLL
bff20000:/WINDOWS/SYSTEM/GDI32.DLL
bff50000:/WINDOWS/SYSTEM/USER32.DLL
bff70000:/WINDOWS/SYSTEM/KERNEL32.DLL
bfea0000:/WINDOWS/SYSTEM/ADVAPI32.DLL
61000000:/SWARM-1.4.1/BIN/CYGWIN1.DLL
66000000:/SWARM-1.4.1/BIN/CYGTCL80.DLL
78810000:/WINDOWS/SYSTEM/WSOCK32.DLL
78850000:/WINDOWS/SYSTEM/WS2HELP.DLL
78000000:/WINDOWS/SYSTEM/MSVCRT.DLL
78860000:/WINDOWS/SYSTEM/WS2_32.DLL
789f0000:/WINDOWS/SYSTEM/WININET.DLL
7b120000:/WINDOWS/SYSTEM/MSWSOCK.DLL
7c110000:/WINDOWS/SYSTEM/MSAFD.DLL
10000000:/PROGRAM FILES/DATA FELLOWS/F-SECURE/ANTI-VIRUS/DFSAV32.DLL
*** event raised for error: InvalidArgument
*** function: _i_Object_s__doesNotRecognize_(), file:
/src/swarm-1.4.1/src/defobj/DefObject.m, line: 635
SwarmActivity_c does not recognize getPeriodActivity*** execution terminating
due to error
warning: cygwin: signal 6


Program exited with code 03000.
(gdb) bt
No stack.
(gdb) break Schedule.m:51
Breakpoint 1 at 0x411160: file Schedule.m, line 51.
(gdb) run
Starting program: /u/mosq/proto/persons.exe
SHELL32.DLL (symbols previously loaded)

[... deleted ...]

MSAFD.DLL (symbols previously loaded)
DFSAV32.DLL (symbols previously loaded)

Breakpoint 1, notifyDrop (obj=0x2ad3ae0, unused=0x0, arg=0x2b097a0)
    at Schedule.m:58
(gdb) bt
#0  notifyDrop (obj=0x2ad3ae0, unused=0x0, arg=0x2b097a0) at Schedule.m:58
#1  0x47cd7b in _i_Object_s__drop (self=0x2ad3ae0, _cmd=0x4daf00)
    at /src/swarm-1.4.1/src/defobj/DefObject.m:196
#2  0x417937 in _i_SmlModelSwarm__dropAgents (self=0x2a6ec58, _cmd=0x4db368)
    at SmlModelSwarm.m:322
#3  0x47d977 in _i_Object_s__perform_ (self=0x2a6ec58, _cmd=0x4ecbf0,
    aSel=0x4db368) at /src/swarm-1.4.1/src/defobj/DefObject.m:511
#4  0x44c6f5 in _i_ActionTo_0___performAction__ (self=0x2b05fe0,
    _cmd=0x4ebf08, anActivity=0x2b088a0)
    at /src/swarm-1.4.1/src/activity/Action.m:211
#5  0x44b138 in _i_Activity_c___run_ (self=0x2b088a0, _cmd=0x4ebef0)
    at /src/swarm-1.4.1/src/activity/XActivity.m:185
#6  0x44b078 in _i_Activity_c___run_ (self=0x2b07dd8, _cmd=0x4ebef0)
    at /src/swarm-1.4.1/src/activity/XActivity.m:143
#7  0x44b078 in _i_Activity_c___run_ (self=0x2b07c60, _cmd=0x4ebef0)
    at /src/swarm-1.4.1/src/activity/XActivity.m:143
#8  0x44b078 in _i_Activity_c___run_ (self=0x2b03428, _cmd=0x4ebef0)
    at /src/swarm-1.4.1/src/activity/XActivity.m:143
#9  0x44b078 in _i_Activity_c___run_ (self=0x2b065d0, _cmd=0x4ebed8)
    at /src/swarm-1.4.1/src/activity/XActivity.m:143
#10 0x44afa7 in _i_Activity_c__run (self=0x2b065d0, _cmd=0x4de698)
    at /src/swarm-1.4.1/src/activity/XActivity.m:72
#11 0x4229ae in _i_ControlPanel__startInActivity_ (self=0x2a5f7c0,
    _cmd=0x4de310, activityID=0x2b065d0)
    at /src/swarm-1.4.1/src/simtoolsgui/ControlPanel.m:99
#12 0x4220e9 in _i_GUISwarm__go (self=0x2a5c9c0, _cmd=0x4d7188)
    at /src/swarm-1.4.1/src/simtoolsgui/GUISwarm.m:47
#13 0x40a9b2 in main (argc=1, argv=0x29c0d20) at TopLevel.m:63
#14 0x61004402 in _size_of_stack_reserve__ ()
#15 0x61004420 in _size_of_stack_reserve__ ()
#16 0x4d34e2 in cygwin_crt0 (f=0x40a88c <main>)
    at /home/noer/src/b20/comp-tools/devo/winsup/libccrt0.cc:81
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x4cb7d9 in objc_msg_lookup ()
(gdb) run
Starting program: /u/mosq/proto/persons.exe
SHELL32.DLL (symbols previously loaded)
COMCTL32.DLL (symbols previously loaded)

[... deleted ...]

MSAFD.DLL (symbols previously loaded)
DFSAV32.DLL (symbols previously loaded)

Breakpoint 1, notifyDrop (obj=0x2ad3b18, unused=0x0, arg=0x2b05248)
    at Schedule.m:58
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x4cb7f7 in objc_msg_lookup ()
(gdb) break SmlModelSwarm.m:303
Breakpoint 2 at 0x4178bb: file SmlModelSwarm.m, line 303.
(gdb) run
Starting program: /u/mosq/proto/persons.exe
SHELL32.DLL (symbols previously loaded)

[... deleted ...]

MSAFD.DLL (symbols previously loaded)
DFSAV32.DLL (symbols previously loaded)

Breakpoint 1, notifyDrop (obj=0x2ad3828, unused=0x0, arg=0x2a80800)
    at Schedule.m:58
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x4cb7fa in objc_msg_lookup ()
(gdb) disable 1
(gdb) run
Starting program: /u/mosq/proto/persons.exe
SHELL32.DLL (symbols previously loaded)
COMCTL32.DLL (symbols previously loaded)

[... deleted ...]

MSAFD.DLL (symbols previously loaded)
DFSAV32.DLL (symbols previously loaded)

Program received signal SIGSEGV, Segmentation fault.
0x4cb7d9 in objc_msg_lookup ()
(gdb) quit



Debugger finished



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