From: os97673@...
Date: 2014-12-04T11:30:57+00:00
Subject: [ruby-core:66687] [ruby-trunk - Bug #10511] fix for #9940 causes dramatic performance regression

Issue #10511 has been updated by Oleg Sukhodolsky.


Koichi Sasada wrote:
> Ok, I understand the reason.
> 
> For each hash access, new Hash object are created each time.

do you mean that it is your code who creates new hash every time?

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Bug #10511: fix for #9940 causes dramatic performance regression
https://bugs.ruby-lang.org/issues/10511#change-50291

* Author: Oleg Sukhodolsky
* Status: Feedback
* Priority: Normal
* Assignee: Koichi Sasada
* Category: core
* Target version: current: 2.2.0
* ruby -v: ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-darwin14.0]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
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Originally reported against debase gem (https://github.com/denofevil/debase/issues/16)
After fix for #9940 running anything under debugger became about 4 times slower.
I've verified that we I revert the fix performance is restored.
To reproduce you could get https://github.com/railstutorial/sample_app_rails_4 and run rspec rake task under debugger (I've used RubyMine for this because debase is used as 
debugger's backend there)
Performance with 2.1.2 it takes about 20 seconds on my laptop, with 2.1.3 - almost 80 seconds :(
The same problem is observable with 2.1.4 and 2.1.5 too.




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