Another null-object crash

[Tee Toth-Fejel]

Java 1.3 Swarm 2.1.1 on Windows NT 4.0 
Running my almost distributed version of jheatbugs in DOS, I get:
C:\SwarmSyncer\jheatbugs>java StartHeatbugs   | tee
HeatbugModelSwarm.buildObjects: Creating heatbugs
< a bunch of my output lines deleted while it runs normally... snip>
#
# HotSpot Virtual Machine Error, EXCEPTION_ACCESS_VIOLATION
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
#
# Error ID: 4F533F57494E13120E43505002D4
#
/src/Swarm/swarm/src/defobj/java.m:808 java_get_class_name
      0 [main] java 1001 sig_send: wait for sig_complete event failed, sig
6, rc 258, Win32 error 0

--------------------------------------------
Looking at the display, I think I know what is happening -- the last heatbug
leaves the local HeatSpace for greener pasture of the remote HeatSpace, and
the schedule calls drawSelfOn on a null object, and the system crashes
without generating a Java exception.  

How can I fix it?  The HeatSpace should be smart enough to not crash just
because all the jheatbugs have left, or more precisely,  ActionGroupImpl
shouldn't call stepRule on Diffuse2d -- or should it not call the scheduled
updateLattice?   It's not clear from the backtrace how drawSelfOn *is* being
called, so I don't know where to put the "try/catch" structure even if there
was an exception generated.

Thanks for any help you can give.

Included is my source code, and here is the gdb output from bash:
--------------------------------------------
address@hidden//c/SwarmSyncer/jheatbugs] $ JAVASWARMGDB=gdb javaswarm
StartHeatbugs
GNU gdb 20000204
Copyright 2000 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 "i686-pc-cygwin"...
(gdb) run
Starting program: /Swarm-2.1.1/libexec/Kaffe.exe 'StartHeatbugs'
61000000:C:/Swarm-2.1.1/bin/cygwin1.dll
77dc0000:C:/WINNT/system32/ADVAPI32.DLL"C:/WINNT/system32/ADVAPI32.DLL":
error reading line numbers

77f00000:C:/WINNT/system32/KERNEL32.dll"C:/WINNT/system32/KERNEL32.dll":
error reading line numbers

77e70000:C:/WINNT/system32/USER32.dll
77ed0000:C:/WINNT/system32/GDI32.dll
77e10000:C:/WINNT/system32/RPCRT4.dll
77bf0000:C:/WINNT/System32/rpcltc1.dll
77800000:C:/WINNT/System32/netapi32.dll
78000000:C:/WINNT/system32/MSVCRT.dll"C:/WINNT/system32/MSVCRT.dll": can't
read symbols: File format
 not recognized.
77840000:C:/WINNT/system32/NETRAP.dll"C:/WINNT/system32/NETRAP.dll": error
reading line numbers

777e0000:C:/WINNT/system32/SAMLIB.dll"C:/WINNT/system32/SAMLIB.dll": error
reading line numbers

warning: LDR: Automatic DLL Relocation in Kaffe.exe

warning: LDR: Dll libkaffeswarm.dll base 10000000 relocated due to collision
with Dynamically Allocated Memory

14470000:C:/Swarm-2.1.1/bin/libkaffeswarm.dll
60540000:C:/Swarm-2.1.1/bin/BLT24.dll
66000000:C:/Swarm-2.1.1/bin/cygtcl80.dll
66300000:C:/Swarm-2.1.1/bin/cygtk80.dll
77d80000:C:/WINNT/system32/COMDLG32.DLL
77c40000:C:/WINNT/system32/SHELL32.dll
71590000:C:/WINNT/system32/COMCTL32.dll"C:/WINNT/system32/COMCTL32.dll":
can't read symbols: File fo
rmat not recognized.
30000000:C:/Program Files/Iomega/Tools_NT/IMGHOOK.DLL"C:/Program
Files/Iomega/Tools_NT/IMGHOOK.DLL":
 can't read symbols: File format not recognized.
warning: LDR: Automatic DLL Relocation in Kaffe.exe

warning: LDR: Dll msh_zwf.dll base 0d2d0000 relocated due to collision with
Dynamically Allocated Me
mory

14e50000:C:/Program Files/Microsoft Hardware/Mouse/msh_zwf.dll
77a90000:C:/WINNT/system32/VERSION.dll"C:/WINNT/system32/VERSION.dll": error
reading line numbers

779c0000:C:/WINNT/system32/LZ32.dll"C:/WINNT/system32/LZ32.dll": error
reading line numbers

71190000:C:/WINNT/system32/MSIDLE.DLL"C:/WINNT/system32/MSIDLE.DLL": can't
read symbols: File format
 not recognized.
HeatbugModelSwarm.buildObjects: Creating heatbugs

< a bunch of my output lines deleted while it runs normally... snip>

Program received signal SIGSEGV, Segmentation fault.
0x417b02 in Kaffe_GetObjectClass (env=0x4573a4, obj=0x0)
    at /src/kaffe/kaffe/kaffevm/jni.c:506
506     /src/kaffe/kaffe/kaffevm/jni.c: No such file or directory.
(gdb) bt
#0  0x417b02 in Kaffe_GetObjectClass (env=0x4573a4, obj=0x0)
    at /src/kaffe/kaffe/kaffevm/jni.c:506
#1  0x1457a096 in _i_FCall_c___setJavaMethod__inObject_ (self=0xa739378,
    _cmd=0x146b4ae0, theMethodName=0xa7393b0 "drawSelfOn", jObj=0x0)
    at /src/Swarm/swarm/src/defobj/FCall.m:341
#2  0x1457a13d in _i_FCall_c__setJavaMethod_inObject_ (self=0xa739378,
    _cmd=0x146b6638, theMethodName=0xa7393b0 "drawSelfOn", jObj=0x0)
    at /src/Swarm/swarm/src/defobj/FCall.m:355
#3  0x14584cbc in _i_JavaCollection__forEach__ (self=0xa7102e0,
    _cmd=0x14677298, sel=0xa70da20, arg1=0xa70cb70)
    at /src/Swarm/swarm/src/defobj/JavaCollection.m:181
#4  0x144d56ba in _i_Object2dDisplay__display (self=0xa613720,
_cmd=0x146732b8)
    at /src/Swarm/swarm/src/space/Object2dDisplay.m:95
#5  0x144c6a55 in Java_swarm_space_Object2dDisplayImpl_display
(env=0x4573a4,
    jobj=0xa2d0710) at space_stubs.m:408
#6  0xa39320b in ?? ()
#7  0xa388c99 in ?? ()
#8  0x416980 in callMethodV (meth=0xa1ec4c8, func=0xa388bd0, obj=0xa2128c8,
    args=0x25ae6b4, ret=0x25ae4a8) at /src/kaffe/config/i386/common.h:45
#9  0x417dcc in Kaffe_CallObjectMethodV (env=0x4573a4, obj=0xa2128c8,
    meth=0xa1ec4c8, args=0x25ae6b4) at /src/kaffe/kaffe/kaffevm/jni.c:564
#10 0x417e44 in Kaffe_CallObjectMethod (env=0x4573a4, obj=0xa2128c8,
    meth=0xa1ec4c8) at /src/kaffe/kaffe/kaffevm/jni.c:581
---Type <return> to continue, or q <return> to quit---
#11 0x14667327 in __builtin_avcall ()
#12 0x145905bb in java_call (fa=0xa73a638)
    at /src/Swarm/swarm/src/defobj/_fcall.m:170
#13 0x1457a729 in _i_FCall_c__performCall (self=0xa72ec30, _cmd=0x146b3e10)
    at /src/Swarm/swarm/src/defobj/FCall.m:610
#14 0x145757bd in _i_Object_s__forward__ (self=0xa6d05b8, _cmd=0xa605b98,
    aSel=0xa6d42b8, argFrame=0x25aec00)
    at /src/Swarm/swarm/src/defobj/DefObject.m:693
#15 0x145caa40 in __objc_forward (object=0xa6d05b8, sel=0xa6d42b8,
    args=0x25aec00) at /src/Swarm/swarm/libobjc/sendmsg.c:571
#16 0x145ca7dd in __objc_word_forward (rcv=0xa6d05b8, op=0xa6d42b8)
    at /src/Swarm/swarm/libobjc/sendmsg.c:499
#17 0x14667327 in __builtin_avcall ()
#18 0x14590b5b in objc_call (fa=0xa7257b8)
    at /src/Swarm/swarm/src/defobj/_fcall.m:170
#19 0x1457a73c in _i_FCall_c__performCall (self=0xa7260e8, _cmd=0x146aadd8)
    at /src/Swarm/swarm/src/defobj/FCall.m:613
#20 0x1455bce7 in _i_ActionTo_c___performAction__ (self=0xa725778,
    _cmd=0x146afe90, anActivity=0xa7351d0)
    at /src/Swarm/swarm/src/activity/Action.m:288
#21 0x14568e81 in _i_Activity_c___run_ (self=0xa7351d0, _cmd=0x146afe70)
    at /src/Swarm/swarm/src/activity/XActivity.m:239
#22 0x14568d8a in _i_Activity_c___run_ (self=0xa729f88, _cmd=0x146afe70)
---Type <return> to continue, or q <return> to quit---
    at /src/Swarm/swarm/src/activity/XActivity.m:189
#23 0x14568d8a in _i_Activity_c___run_ (self=0xa7395e8, _cmd=0x146afe70)
    at /src/Swarm/swarm/src/activity/XActivity.m:189
#24 0x14568d8a in _i_Activity_c___run_ (self=0xa728760, _cmd=0x146afe28)
    at /src/Swarm/swarm/src/activity/XActivity.m:189
#25 0x14568b53 in _i_Activity_c__run (self=0xa728760, _cmd=0x1467d2e0)
    at /src/Swarm/swarm/src/activity/XActivity.m:76
#26 0x144e3519 in _i_ControlPanel__startInActivity_ (self=0xa6d5f60,
    _cmd=0x1467db28, activityID=0xa728760)
    at /src/Swarm/swarm/src/simtoolsgui/ControlPanel.m:100
#27 0x144e4510 in _i_GUISwarm__go (self=0xa6d05b8, _cmd=0x146713a8)
    at /src/Swarm/swarm/src/simtoolsgui/GUISwarm.m:56
#28 0x144b214d in Java_swarm_simtoolsgui_GUISwarmImpl_go (env=0x4573a4,
    jobj=0xa2128c8) at simtoolsgui_stubs.m:123
#29 0xa33e74b in ?? ()
#30 0xa1f0db1 in ?? ()
#31 0x416950 in callMethodV (meth=0xa179e14, func=0xa1ce9e8, obj=0x0,
    args=0x25af8f8, ret=0x25af6fc) at /src/kaffe/config/i386/common.h:38
#32 0x41d68d in Kaffe_CallStaticVoidMethodV (env=0x4573a4, cls=0xa160648,
    meth=0xa179e14, args=0x25af8f8) at /src/kaffe/kaffe/kaffevm/jni.c:2343
#33 0x41d6fb in Kaffe_CallStaticVoidMethod (env=0x4573a4, cls=0xa160648,
    meth=0xa179e14) at /src/kaffe/kaffe/kaffevm/jni.c:2356
#34 0x401303 in main2 (env=0x4573a4, argv=0xa040fe0, farg=2, argc=0)
---Type <return> to continue, or q <return> to quit---
    at /src/kaffe/kaffe/kaffe/main.c:193
#35 0x401198 in main (argc=2, argv=0xa040fe0)
    at /src/kaffe/kaffe/kaffe/main.c:113
#36 0x610022c5 in libtk80_a_iname ()
#37 0x61002855 in libtk80_a_iname ()
#38 0x45667f in cygwin_crt0 ()
#39 0x40103b in mainCRTStartup ()
#40 0x77f1b9ea in ?? ()
(gdb)
--------------------------


Tihamer "Tee" Toth-Fejel                    Member of Technical Staff
(734) 623-2544   address@hidden      http://www.erim.org/ 
Center for Electronic Commerce, Environmental Research Institute of Michigan

SemiDistributedJHeatbugs.zip
Description: Binary data