From: pdahorek@...
Date: 2017-07-31T14:22:49+00:00
Subject: [ruby-core:82217] [Ruby trunk Bug#13167] Dir.glob is 25x slower	since Ruby 2.2

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


there's a good article about this
https://research.swtch.com/glob
https://perl5.git.perl.org/perl.git/commitdiff/33252c318625f3c6c89b816ee88481940e3e6f95?hp=57ab6c610267dba697199c8256f4258af7d391c1

take a look at the python's implementation
https://github.com/python/cpython/commits/3.6/Lib/glob.py

Ruby has tons of ifs, gotos and recursions for many special cases, it's not very readable and I have a tough time to understand what's happening
For instance this Windows problem is solved, Python has different approach, because results of the glob will be the same even with the previous Ruby 2.1 implementation, you just need to normalize the output according to realpaths (I expect that I can't create two files or directories with a same name like "test.txt" and "Test.txt", am I right?)

simplier example
```
Dir.glob("c:/test/myapp")
```
Python
CreateFile
QueryInformationVolume
QueryAllInformationFile
CloseFile

Ruby 2.1
CreateFile
QueryNetworkOpenInformationFile
CloseFile

Ruby 2.4.1
CreateFile
QueryNetworkOpenInformationFile
CloseFile
CreateFile
QueryNetworkOpenInformationFile
CloseFile
CreateFile
QueryNetworkOpenInformationFile
CloseFile
CreateFile
QueryNetworkOpenInformationFile
CloseFile
QueryFirectory
CloseFile
CreateFile
QueryNetworkOpenInformationFile
CloseFile
CreateFile
QueryDirectory
CloseFile

I think that Python has fully compatible syntax, even with {} expansion and also works fast on Windows (case sensitive)


----------------------------------------
Bug #13167: Dir.glob is 25x slower since Ruby 2.2
https://bugs.ruby-lang.org/issues/13167#change-65984

* Author: ahorek (Pavel Rosick��)
* 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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