[MacRuby-devel] How can I catch segment faults?

[Laurent Sansonetti]

Hi,

We will implement dwarf symbolication which will allow you to see the  
ruby method, filename and line instead of ?? in the gdb backtrace, but  
in the meantime an easy way to debug these problems is to toggle the  
ROXOR_VM_DEBUG variable to 1 in vm.cpp and recompile miniruby.

This will print a lot of information on stdout, which should allow you  
to track and identify the crash.

# Segmentation faults are bugs in MacRuby core, so in theory users  
should not see them :)

Also, try setting the GC_DISABLE environment variable to 1 before  
starting the program, if it doesn't crash then it's very likely a  
missing write barrier in the collector.

Laurent

On Sep 20, 2009, at 3:03 AM, B. Ohr (dev) wrote:

>
> Hey, after installing r2590 with backtrace support (thanks for  
> that!) now I have the problem to catch segment faults.
>
> It seems to be a problem inside of a hash#each_pair, but I have  
> absolutely no idea where, and because it is foreign code a file name  
> and line number would be more than useful!
>
> -------
>
> (gdb) run ../xx.rb compile
> Starting program: /usr/local/bin/macruby ../xx.rb compile
> Reading symbols for shared libraries + done
> Loading site data...
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_INVALID_ADDRESS at address: 0x00007fff60771b60
> 0x0000000100d90283 in _cache_getMethod ()
>
> (gdb) backtrace
> #0  0x0000000100d90283 in _cache_getMethod ()
> #1  0x0000000100d8fa43 in look_up_method ()
> #2  0x0000000100176c4d in __rb_vm_dispatch [inlined] () at /Users/ 
> box/Documents/dev/macruby/macruby/vm.cpp:2780
> #3  0x0000000100176c4d in rb_vm_dispatch (cache=0x108fcfac0,  
> self=140734799741824, sel=0x102b8b570, block=0x0, opt=0 '\0',  
> argc=1) at vm.cpp:3154
> #4  0x0000000104152605 in ?? ()
> #5  0x00000001001752b6 in rb_vm_yield0 [inlined] () at /Users/box/ 
> Documents/dev/macruby/macruby/vm.cpp:4207
> #6  0x00000001001752b6 in rb_vm_yield (argc=6687904,  
> argv=0x7fff5fbf56f0) at vm.cpp:4214
> #7  0x000000010011a978 in rb_yield_0 [inlined] () at /Users/box/ 
> Documents/dev/macruby/macruby/vm_eval.c:194
> #8  0x000000010011a978 in rb_yield_values (n=<value temporarily  
> unavailable, due to optimizations>) at vm_eval.c:226
> #9  0x0000000100039c68 in inject_i (i=1, p=140734799741792,  
> argc=6753408, argv=0x7fff5fbf5988) at enum.c:429
> #10 0x00000001001741da in rb_vm_block_eval0 (b=0x2006403c0, sel=0x0,  
> self=8596725184, argc=1, argv=0x10a64a860) at vm.cpp:4082
> #11 0x00000001001752b6 in rb_vm_yield0 [inlined] () at /Users/box/ 
> Documents/dev/macruby/macruby/vm.cpp:4207
> #12 0x00000001001752b6 in rb_vm_yield (argc=1, argv=0x7fff5fbf5988)  
> at vm.cpp:4214
> #13 0x000000010011a1f0 in rb_yield (val=8596688000) at vm_eval.c:194
> #14 0x000000010004d5f7 in each_pair_i (key=8596688000, value=0) at  
> hash.c:1099
> #15 0x0000000100050c2c in rb_hash_foreach (hash=<value temporarily  
> unavailable, due to optimizations>, func=0x10004d5e0 <each_pair_i>,  
> farg=0) at hash.c:108
> #16 0x0000000100051321 in rb_hash_each_pair (hash=8596722368,  
> sel=0x102b2b400) at hash.c:1125
> #17 0x00000001001738e1 in rb_vm_call_with_cache2 (cache=0x102b2b490,  
> block=0x2006403c0, self=8596722368, klass=4295299792,  
> sel=0x102b2b400, argc=<value temporarily unavailable, due to  
> optimizations>, argv=0x0) at vm.cpp:2336
> #18 0x0000000100037fd8 in enum_inject (obj=8596722368, sel=<value  
> temporarily unavailable, due to optimizations>, argc=<value  
> temporarily unavailable, due to optimizations>, argv=<value  
> temporarily unavailable, due to optimizations>) at enum.c:521
> #19 0x0000000100177be1 in rb_vm_dispatch (cache=0x106e620b0,  
> self=8596722368, sel=0x102b51b30, block=0x200640420, opt=2 '\002',  
> argc=1) at vm.cpp:2679
> #20 0x0000000104152410 in ?? ()
> #21 0x0000000104151afe in ?? ()
> #22 0x000000010415173b in ?? ()
> #23 0x000000010006cbe7 in rb_class_new_instance_imp (klass=1,  
> sel=<value temporarily unavailable, due to optimizations>,  
> argc=6755200, argv=0x104152390) at object.c:1892
> #24 0x0000000100177be1 in rb_vm_dispatch (cache=0x102b69670,  
> self=8596901376, sel=0x102b2d8b0, block=0x0, opt=0 '\0', argc=1) at  
> vm.cpp:2679
> #25 0x000000010414fe2f in ?? ()
> #26 0x000000010414f785 in ?? ()
> #27 0x000000010413812e in ?? ()
> #28 0x000000010414c561 in ?? ()
> #29 0x00000001040808f2 in ?? ()
> #30 0x000000010003f809 in ruby_run_node (n=0x200662500) at eval.c:198
> #31 0x0000000100000dd8 in main (argc=3, argv=0x102b1ba90,  
> envp=<value temporarily unavailable, due to optimizations>) at  
> main.cpp:42
>
>
> _______________________________________________
> MacRuby-devel mailing list
> MacRuby-devel at lists.macosforge.org
> http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel