# Why does Exception#backtrace hate me so?

**URL:** <https://www.ruby-forum.com/t/why-does-exception-backtrace-hate-me-so/87974>\
**Category:** Ruby\
**Created:** [March 7, 2007, 9:18am UTC](https://www.ruby-forum.com/t/why-does-exception-backtrace-hate-me-so/87974 "2007-03-07T09:18:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![kelleysislander](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/f6c823/32.png) [@kelleysislander](https://www.ruby-forum.com/u/kelleysislander)\
**Post date:** [March 7, 2007, 9:18am UTC](https://www.ruby-forum.com/t/why-does-exception-backtrace-hate-me-so/87974/1 "2007-03-07T09:18:30Z")

</div>

Hi,

I’m compiling a lot of ruby code via eval, and running parts of  
it in $SAFE=4, and I’m noticing large gaps in the Exception  
backtraces. (I’ve done experiments with Kernel#caller, and the  
gaps are usually there, too.)

Here’s an example backtrace I’m getting:

#\<SecurityError: relative …/ not allowed in path\>  
(eval):185:in `get_fullpath' (eval):451:in`value’  
(eval):451:in `sandbox' (eval):538:in`kickoff\_background\_export’  
(eval):1253:in `kickoff_progress_task' (eval):1250:in`kickoff\_progress\_task’  
(eval):1235:in `handle_progress_timer' (eval):1194:in`init\_dialog’  
(eval):418:in `dispatch_event' (eval):540:in`dispatch\_event’  
(eval):129:in `create_sandbox_binding' (eval):129:in`create\_sandbox\_binding’  
(eval):93:in `run' (eval):166:in`dispatch\_new\_contexts’  
(eval):166:in `dispatch_new_contexts' (eval):156:in`run’  
(eval):24

This is a fairly typical example of what I’m seeing.  
get\_fullpath is indeed the method that raised the  
exception. But there are several methods in the  
call chain between “get\_fullpath” and “value” that  
are missing.

It should have looked like this:

```
(eval):185:in `get_fullpath'

```

! (eval):???:in `template_dest_mkdir' ! (eval):???:in` **do\_proxy** ’  
~~~~~~~~~~~~~~~~~~~~~~~~~~ (note: thread boundary)  
! (eval):???:in `method_missing' ! (eval):???:in`generate\_css’  
! (eval):???:in `generate\_site’

```
 ~~~~~~~~~~~~~~~~~~~~~~~~~~ (note: thread boundary)
(eval):451:in `value'
(eval):451:in `sandbox'
 etc. . .

```

Now I could understand possible difficulties with  
picking up the call chain across thread boundaries  
(meaning: cases like Thread.new{$SAFE=4; foo()}.value)

But, parts of the call chain are missing before we get  
to a thread boundary. For ex., the “template\_dest\_mkdir”  
and “ **do\_proxy** ” callers are just completely normal,  
with respect to being the immediate callers of  
“get\_fullpath”, and yet they’re missing from the  
backtrace, too.

Anyway, I guess what I’m wondering is whether this  
might be a known issue or have a reasonable explanation,  
or whether it’s unexpected behavior?

If it’s unexpected behavior, then I’ll be happy to try  
to write a simpler test case that reproduces the  
problem.

(Note: It’s ruby 1.8.4 (2005-12-24) [i386-mswin32])

Thanks for your help,

Regards,

Bill