How to debug segmentation fault?

[Adrian Salceanu]

I ran into an issue where apparently at random I get segmentation faults - how can I find out what exactly is causing the problem? 

Here is the dump: 

signal (11): Segmentation fault: 11
julia_call_23669 at  (unknown line)
disposable_instance at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Model.jl:647
to_select_part at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Model.jl:262
to_fetch_sql at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Model.jl:542
find at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Model.jl:40
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
find_one_by at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Model.jl:55
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
current_user at /Users/adrian/Dropbox/Projects/jinnie/app/resources/users/model.jl:64
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/gf.c:1691
with_authorization at /Users/adrian/Dropbox/Projects/jinnie/app/resources/users/model.jl:82
articles at /Users/adrian/Dropbox/Projects/jinnie/app/resources/articles/./modules/AdminController.jl:6
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
jl_f_invoke at /private/tmp/julia-20160615-15177-tdcnou/src/builtins.c:1114
invoke_controller at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Router.jl:187
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
match_routes at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Router.jl:73
route_request at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/Router.jl:44
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
anonymous at /Users/adrian/Dropbox/Projects/jinnie/lib/Genie/src/AppServer.jl:18
on_message_complete at /Users/adrian/.julia/v0.4/HttpServer/src/HttpServer.jl:400
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
on_message_complete at /Users/adrian/.julia/v0.4/HttpServer/src/RequestParser.jl:104
jlcapi_on_message_complete_21686 at  (unknown line)
http_parser_execute at /Users/adrian/.julia/v0.4/HttpParser/deps/usr/lib/libhttp_parser.dylib (unknown line)
http_parser_execute at /Users/adrian/.julia/v0.4/HttpParser/src/HttpParser.jl:92
process_client at /Users/adrian/.julia/v0.4/HttpServer/src/HttpServer.jl:365
jlcall_process_client_23170 at  (unknown line)
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
anonymous at task.jl:447
jl_apply at /private/tmp/julia-20160615-15177-tdcnou/src/./julia.h:1331
[1]    50892 segmentation fault  ./genie.jl s

and this is the last known function (which works ok in different circumstances): 

function disposable_instance{T<:AbstractModel}(m::Type{T})
  if m <: AbstractModel
    return m()
  else
    error("$m is not a concrete subtype of AbstractModel")
  end
end

[Jacob Quinn]

There are many much more knowledgeable than me on this, but I know there's a good section in the manual to help you get started: http://docs.julialang.org/en/latest/devdocs/C/

-Jacob

[Adrian Salceanu]

Thanks Jacob

Huhm, probably not worth spending time with debug builds of v0.4 when 0.5 is just around the corner. Think it's time to upgrade to 0.5 and debug that if needed.