Issue #8366 has been updated by anuraguniyal (anurag uniyal).


nobu (Nobuyoshi Nakada) wrote:
> You can see the reason by reducing the size of the instance variable.

What do you mean? I have a big project where I load plugins and each plugin can have megabytes of data and if one plugin does not implement some method, ex.message just hangs, other than that this is huge development nightmare when a typo in code can make scripts hang

It is a bug in NameError#to_s (https://github.com/ruby/ruby/blob/ruby_2_0_0/error.c#L1088-L1095) because it calls obj.inspect and which can be huge and time consuming for objects which have huge instance variables, doesn't Ruby support large instance variables?

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Bug #8366: Exception.message take time to execute depending on the instance variables
https://bugs.ruby-lang.org/issues/8366#change-39119

Author: anuraguniyal (anurag uniyal)
Status: Open
Priority: High
Assignee: 
Category: 
Target version: 
ruby -v: ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin11.4.2]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


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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