Re: SystemStackError 1.8.6 (stack only 25 frames)

I am following up on this topic. Hopefully in the future someone in  
need will come across this in a search engine.

The problem I reported is the result of a deceptive reporting by ruby  
of the backtrace when 'stack too deep' occurs. That is to say, it was  
a wild goose chase looking for causes because the cause was under  
reported.

Ruby gives no indication of recursion in the back trace. From an  
initial function call to a recursive call, the stack will only list  
that function once. Without any indication of recursion, it appears  
in the stack trace that it just stopped.

This particular problem was the result of a source file being  
reloaded with functions that contain aliases of original methods,  
resulting in that method calling itself (forever).

The backtrace needs to have some indication of recursion. Probably  
not a literal printing of recurring stack frames, but maybe something  
like: [15 recursions]. This would make the stack more accurate and  
these problems less misleading. It might not be bad to have a safety  
option for alias to prevent overwriting a target method (redefining a  
method via alias).

Dan


On Oct 18, 2007, at 23:35, Dan Janowski wrote:

> Hi,
>
> I am trying to resolve a SystemStackError that seems to be the  
> result of corruption.
>
> The complete reported stack trace is only 25 frames (stack trace  
> below).
>
> There are some important facts to note:
>
> 1. This only happens after the ra_account.rb has been re-loaded  
> into the same ruby exec when changed
> 2. the stack frame ra_account.rb:153 has no call path from the next  
> upper frame.
> 3. ra_account.rb:153 is this:
>
>         begin
> 153:      raise StandardError, "foo"
>         rescue StandardError
>         end
>
> 4. This is running within Apache/mod_ruby
>
> My hypothesis is the caught exception is interacting with the re- 
> allocation of nodes during re-parsing of an already loaded class  
> and  is either causing stack pointer to be lost, or the beginning  
> is being blown. Of course, I do not understand the allocation  
> system, nor nodes, but I have done quite a bit of ruby extension  
> writing, so I have stepped around some of the stuff.
>
> I have been unable to create a stand alone test case.
>
> I can catch this in GDB, but what do I look for?
>
> Thanks for your consideration.
>
> Dan
>
>
> stack level too deep (SystemStackError)
> /home/danj/devl/www/rb/ra_account.rb:26:in `created_orig'
>         /home/danj/devl/www/rb/ra_account.rb:26:in `created_orig'
>         /home/danj/devl/www/rb/ra_account.rb:26:in `created'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:835:in  
> `send'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:835:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:831:in  
> `each'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:831:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:828:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/rb/ra_account.rb:153:in `each_with_index'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:826:in  
> `each'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:826:in  
> `each_with_index'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:826:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:847:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:831:in  
> `each'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:831:in  
> `emit_hdf_aux'
>         /home/danj/devl/www/wsa/libruby/field_class_xml.rb:818:in  
> `emit'
>         /home/danj/devl/www/rb/ra_account.rb:159:in `local_handler'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:218:in  
> `handler_part2'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:217:in `catch'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:217:in  
> `handler_part2'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:216:in `catch'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:216:in  
> `handler_part2'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:210:in `catch'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:210:in  
> `handler_part2'
>         /home/danj/devl/www/rb/app_shopping_handler.rb:115:in  
> `handler'
>         /home/danj/devl/www/rb/app_apache.rb:41:in `handler'
>
>