[erlang-questions] dialyzer orelse filter slowness

Kostis Sagonas <>
Thu Mar 26 09:30:26 CET 2009


Nick Conrad wrote:
> Hello,
> 
> I've got a module that dialyzer takes more than 15 minutes to analyze,  
> and I've narrowed down the cause to a fairly long orelse expression  
> that is being used as a filter in a list comprehension.  If I replace  
> the orelse expression with a function call and make each individual  
> test it's own function, dialyzer is much happier and completes within  
> seconds.  Does anyone have an explanation for why dialyzer might take  
> so long on the orelse's when used as a filter?
> 
> Here's a bit of code that demonstrates the issue, which I've seen  
> using both R11B and R12B.
>    [CODE SNIPPED]
> 
> % dialyzer --no_check_plt --src -c .
>   Proceeding with analysis... done in 0m0.23s
> done (passed successfully)
> 
> % dialyzer -DUSE_ORELSE=1 --no_check_plt --src -c .
>   Proceeding with analysis... done in 0m32.24s
> done (passed successfully)

In all probability, this has to do with the convoluted translation of 
orelse in R11B and R12B.  In R13* orelse's (and andalso's) translation 
has changed and is much more sane.  I suggest that you switch to R13A 
(there are many other reasons to).

% dialyzer -v
Dialyzer version v1.9.0
% dialyzer -n -c or_else.erl
   Proceeding with analysis... done in 0m0.68s
done (passed successfully)
% dialyzer -DUSE_ORELSE=1 -n -c or_else.erl
   Proceeding with analysis... done in 0m0.91s
done (passed successfully)


Kostis



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