[ruby-core:82150] [Ruby trunk Bug#13167] Dir.glob is 25x slower since Ruby 2.2

Issue #13167 has been updated by ahorek (Pavel Rosick箪).

File logruby24.txt added
File logruby21.txt added

I used Procmon.exe https://live.sysinternals.com to monitor system calls
and it looks like ruby 2.4.1 is traversing the whole directory tree over and over again for each {} matcher. This should be definitely avoided!

take a look, the same single call for a Dir.glob takes
**30** sys-calls on Ruby 2.1.9 but **2086** sys-calls on Ruby 2.4.1!

Ruby 2.1.9 just tries to open all combinations without checking the directory structure

~~~ bash
c:/test/myapp/app/views/common/_menu_stats.en.html.erb open
c:/test/myapp/app/views/common/_menu_stats.en.html.builder open
...
~~~


but Ruby 2.4.1 behaves like this

~~~ bash
c:/ open
c:/ stats
c:/ close
c:/test open
c:/test stats
c:/test close
c:/myapp open
c:/myapp stats
c:/myapp close
...
c:/test/myapp/app/views/common/_menu_stats.en.html.erb open
c:/test/myapp/app/views/common/_menu_stats.en.html.erb stats
c:/test/myapp/app/views/common/_menu_stats.en.html.erb close
*** AND AGAIN ***
c:/ open
c:/ stats
c:/ close
c:/test open
c:/test stats
c:/test close
c:/myapp open
c:/myapp stats
c:/myapp close
...
c:/test/myapp/app/views/common/_menu_stats.en.html.builder open
c:/test/myapp/app/views/common/_menu_stats.en.html.builder stats
c:/test/myapp/app/views/common/_menu_stats.en.html.builder close
*** AND AGAIN ***
c:/ open
c:/ stats
c:/ close
c:/myapp open
c:/myapp stats
c:/myapp close
etc ...
~~~

----------------------------------------
Bug #13167: Dir.glob is 25x slower since Ruby 2.2
https://bugs.ruby-lang.org/issues/13167#change-65905

* Author: ahorek (Pavel Rosick箪)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.4.0
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
Hello,
we've found a huge speed regression in our Rails app. After some digging the reason is in `Dir.glob` method which is much slower since Ruby 2.2.6. This is probably Windows only!

This code is used heavily in Rails for partial lookups:

```ruby
Dir.glob('c:/test/myapp/app/views/common/_menu_stats{.en,}{.html,}{}{.erb,.builder,.raw,.ruby,.jbuilder,.coffee,}')
```

Comparsion (x64):
jruby 9.1.7.0 2540 i/s
ruby 2.1.5 2568 i/s
ruby 2.1.9 2569 i/s
**ruby 2.2.6 99 i/s 25 times slower!
ruby 2.3.3 102 i/s
ruby 2.4.0 103 i/s**

I would like to help, but I don't know much about Ruby C internals. Please let me know if you need any additional info. Now we're stuck at 2.1.9 because this issue makes the development on more recent versions unusable.

---Files--------------------------------
logruby24.txt (484 KB)
logruby21.txt (10.8 KB)


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