[LuaJIT] Backtracing in GDB

[Alex <initrd.gz@...>]

I'm writing a client/server pair in LuaJIT + ffi + enet in Windows 7 and am running into some issues which I cannot seem to pinpoint. Shortly after sending a packet from server to client, I'm faced with weird out-of-memory errors and stalls. Additionally, even though I have both enet and LuaJIT compiled with debug symbols, when I run GDB on it, I get this oddity:

(gdb) set debug jit 1

(gdb) target exec luajit.exe

jit_inferior_init

(gdb) run src/main_server.lua

jit_inferior_init

Starting program: c:\...\luajit.exe src/main_server.lua

[New Thread 224.0x11c8]

jit_inferior_init

jit_inferior_init, descriptor_addr = 0x66dd1004

jit_breakpoint_re_set_internal, breakpoint_addr = 0x66db2120

jit_inferior_init

jit_inferior_init

jit_inferior_init, descriptor_addr = 0x66dd1004

jit_breakpoint_re_set_internal, breakpoint_addr = 0x66db2120

jit_inferior_init, descriptor_addr = 0x66dd1004

... some server output ...

04/23/12 20:22:16 Info - main: Server starting, press 'q' to stop.

jit_register_code, symfile_addr = 0x3802f4, symfile_size = 3109556322304

04/23/12 20:22:26 Info - server: 127.0.0.1 connecting

... some more server loading / output ...

jit_register_code, symfile_addr = 0x39bcec, symfile_size = 3092376453120

jit_register_code, symfile_addr = 0x36f704, symfile_size = 3126739678536

jit_register_code, symfile_addr = 0x3548bc, symfile_size = 3161099416904

jit_register_code, symfile_addr = 0x36a324, symfile_size = 3109559809352

jit_register_code, symfile_addr = 0x3452c4, symfile_size = 3092379940168

04/23/12 20:22:26 Debug - server: Sending data to 127.0.0.1

04/23/12 20:22:26 Debug - server: Data sent

warning: HEAP[luajit.exe]:

warning: Heap block at 003ABBF8 modified at 003ABC6E past requested size of 6e

Program received signal SIGTRAP, Trace/breakpoint trap.

0x776204e5 in ntdll!TpWaitForAlpcCompletion () from C:\windows\system32\ntdll.dll

(gdb) backtrace

#0  0x776204e5 in ntdll!TpWaitForAlpcCompletion () from C:\windows\system32\ntdll.dll

#1  0x0028f900 in ?? ()

#2  0x77605732 in ntdll!RtlLargeIntegerDivide () from C:\windows\system32\ntdll.dll

#3  0x003abbf8 in ?? ()

#4  0x775e29fa in ntdll!RtlCopyExtendedContext () from C:\windows\system32\ntdll.dll

#5  0x00000000 in ?? ()

(gdb) kill

Kill the program being debugged? (y or n) y

jit_inferior_init

jit_inferior_init

jit_inferior_init, descriptor_addr = 0x66dd1004

jit_breakpoint_re_set_internal, breakpoint_addr = 0x66db2120

jit_inferior_init, descriptor_addr = 0x66dd1004

(gdb) quit

I'm not quite sure if this is an error inside of enet or my ffi code, and every time I debug LuaJIT in GDB I always get these unhelpful backtraces. How would I get some useful info about where this issue is occurring, aside from adding print()s everywhere?

Thanks, Alex.