[ruby-core:65207] [ruby-trunk - Feature #8366] [Open] Exception.message take time to execute depending on the instance variables

Issue #8366 has been updated by Nobuyoshi Nakada.

Tracker changed from Bug to Feature
Status changed from Closed to Open

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Feature #8366: Exception.message take time to execute depending on the instance variables
https://bugs.ruby-lang.org/issues/8366#change-49044

* Author: anurag uniyal
* Status: Open
* Priority: Low
* Assignee: 
* Category: core
* Target version: 
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I am seeing very interesting and catastrophic behavior with ruby, see the code below

    class ExceptionTest
    
      def test
        @result = [0]*500000
    
        begin
          no_such_method
        rescue Exception => ex
          puts "before #{ex.class}"
          st = Time.now
          ex.message
          puts "after #{Time.now-st} #{ex.message}"
        end
    
      end
    end
    
    ExceptionTest.new.test

Ideally ex.message should not take any time to execute and hence Time taken should be in ms, but here is the output

    ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin11.4.2]
    before NameError
    after 0.462443 undefined local variable or method `no_such_method' for #<ExceptionTest:0x007fc74a84e4f0>

If I assign `[0]*500000` to a local variable instead of instance variable e.g. `result = [0]*500000` it runs as expected

    ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin11.4.2]
    before NameError
    after 2.8e-05 undefined local variable or method `no_such_method' for #<ExceptionTest:0x007ff59204e518>

**It looks like somehow `ex.message` is looping thru the instance variables, why it would do so, please enlighten me!**

I have tried it on ruby ruby-1.9.2-p290, ruby-1.9.1-p376 and whatever version the ruby on codepad.org is.




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