Issue #15856 has been updated by Dan0042 (Daniel DeLorme).


Without the patch:

```ruby
require "digest"
p Digest::SHA256 #=> Digest::SHA256
p Digest::SHA2   #=> Digest::SHA2
```

With the patch:

```ruby
require "digest"
p Digest::SHA256 #=> Digest::SHA256
p Digest::SHA2   #=> uninitialized constant Digest::SHA2
```

The fix in digest.rb is simple enough:

```
   def self.const_missing(name) # :nodoc:
     case name
     when :SHA256, :SHA384, :SHA512
-      lib = 'digest/sha2.so'
+      lib = 'digest/sha2.rb'
     else
```


----------------------------------------
Bug #15856: Performance of redundant `Kernel.require` is slow when many gems are activated
https://bugs.ruby-lang.org/issues/15856#change-87162

* Author: lamont (Lamont Granquist)
* Status: Assigned
* Priority: Normal
* Assignee: hsbt (Hiroshi SHIBATA)
* ruby -v: ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
With many gems activated, performance of `Kernel.require` (renamed `Kernel.gem_original_require` after rubygems is loaded) is slow even when `require` has already been called (the redundant case).

This is likely because its string argument needs to be resolved to a pathname in order to be compared against a cache of already loaded paths shared between `require` and `require_relative`. But it becomes very expensive with lots of activated gems, particularly on windows, where `open`/`stat` is ten times more expensive than on linux.

`require` (but not `require_relative`, which is already fast) probably needs another layer of redundancy checking that examines if the string argument exists as a `Hash` key (which I believe is the way `require` used to work before `require_relative` was introduced).  The second time a `require` line is processed, it would find the value `true` and short circuit File I/O to resolve the filename.  Of course on the first time, it would still need to resolve the argument to full path and maintain the cache so that `require` and `require_relative` are still redundant between them.

After testing, I don't think this would introduce any behavior changes since `require` lines should always be redundant.  I thought it would fix some bugs, but I could not let the existing loader double-load a `require` line even though I tried to install and activate gems after requiring system libs.  I couldn't find any bugs, though, which also means that this should be backward compatible.

An strace of the process of a single `require "openssl"` after it has been already required looks like this:

```
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/uuidtools-2.1.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-bin-15.0.276/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/public_suffix-3.0.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/addressable-2.6.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-shellout-2.4.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-cli-2.0.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/appbundler-0.12.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/bcrypt_pbkdf-1.0.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/bcrypt_pbkdf-1.0.1/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/debug_inspector-0.0.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/debug_inspector-0.0.3/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/binding_of_caller-0.8.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/binding_of_caller-0.8.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/builder-3.2.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/byebug-11.0.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/byebug-11.0.1/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tomlrb-1.2.8/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-config-3.0.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/fuzzyurl-0.9.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-config-15.0.276/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/net-ssh-5.2.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/net-scp-2.0.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/erubis-2.7.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ffi-1.10.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/ffi-1.10.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/gssapi-1.3.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/gyoku-1.3.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/httpclient-2.8.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/little-plugger-1.1.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/multi_json-1.13.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/logging-2.2.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/nori-2.6.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rubyntlm-0.6.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/winrm-2.3.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rubyzip-1.2.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/winrm-fs-1.3.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/train-core-2.1.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/equatable-0.5.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-color-0.4.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/pastel-0.7.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-cursor-0.6.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/strings-ansi-0.1.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/unicode_utils-1.4.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/unicode-display_width-1.4.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/strings-0.1.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-box-0.3.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/necromancer-0.4.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/timers-4.3.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/wisper-2.0.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-screen-0.6.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-reader-0.5.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-prompt-0.18.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/license-acceptance-1.0.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-log-3.0.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-authentication-2.1.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/mixlib-archive-1.0.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/systemu-2.6.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/libyajl2-1.2.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/libyajl2-1.2.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ffi-yajl-2.3.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/ffi-yajl-2.3.1/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/plist-3.5.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ipaddress-0.8.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/wmi-lite-1.0.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ohai-15.0.34/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/net-ssh-gateway-2.0.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/net-ssh-multi-1.2.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/net-sftp-2.1.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ed25519-1.2.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/ed25519-1.2.4/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/highline-1.7.10/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/diff-lcs-1.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ffi-libarchive-0.4.6/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/hashie-3.6.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/uuidtools-2.1.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-zero-14.0.12/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/iniparse-1.4.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/syslog-logger-1.6.8/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/proxifier-1.0.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-15.0.276/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-bin-15.0.276/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/chef-vault-3.4.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/cheffish-14.0.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/coderay-1.1.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/safe_yaml-1.0.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/crack-0.4.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/docile-1.3.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/multipart-post-2.0.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/faraday-0.15.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/faraday_middleware-0.12.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/hashdiff-0.3.9/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/htmlentities-4.3.4/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/method_source-0.9.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-support-3.8.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-core-3.8.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-expectations-3.8.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-mocks-3.8.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-3.8.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec-its-1.3.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/pry-0.12.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/sslshake-1.3.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/parallel-1.17.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/parslet-1.8.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/semverse-3.0.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tty-table-0.10.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/tins-1.20.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/term-ansicolor-1.7.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/inspec-core-4.3.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/json-2.2.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/json-2.2.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/pry-byebug-3.7.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/slop-3.6.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/pry-remote-0.1.8/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/pry-stack_explorer-0.4.9.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rake-12.3.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rb-readline-0.5.5/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/rspec_junit_formatter-0.2.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ruby-prof-0.17.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/ruby-prof-0.17.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/ruby-shadow-2.5.0/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/extensions/x86_64-linux/2.6.0/ruby-shadow-2.5.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/simplecov-html-0.10.2/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/simplecov-0.16.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/webmock-3.5.1/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/gems/2.6.0/gems/bundler-1.17.3/lib/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/site_ruby/2.6.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/site_ruby/2.6.0/x86_64-linux/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/site_ruby/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/vendor_ruby/2.6.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/vendor_ruby/2.6.0/x86_64-linux/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/vendor_ruby/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/opt/chef/embedded/lib/ruby/2.6.0/openssl.rb", O_RDONLY|O_NONBLOCK|O_CLOEXEC) = 7
```

On windows, this much I/O on every single `require` line can quickly add up to 100,000s of open calls, which takes several seconds on an SSD or up to a minute on a spinning drive just to evaluate the requires of an application that does no work (i.e. command line tooling).



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>