Memory Use exploded in 2.6 #812
Description
Rails 4.2 is moving to Mail 2.6.1 and i'm seeing a huge increase in memory usage in my running application. After some digging, it looks like the culprit was the Mail version bump.
To demonstrate the issue, here's a script to reproduce without rails:
Build Gemfiles
$ mkdir 2.6.1
$ cat << EOF > 2.6.1/Gemfile
source 'https://rubygems.org'
gem 'mail', '2.6.1'
gem 'get_process_mem'
EOF
$ mkdir 2.5.4
$ cat << EOF > 2.5.4/Gemfile
source 'https://rubygems.org'
gem 'mail', '2.5.4'
gem 'get_process_mem'
EOF
Install
$ env BUNDLE_GEMFILE=2.6.1/gemfile bundle install
$ env BUNDLE_GEMFILE=2.5.4/gemfile bundle install
Test script
$ cat << EOF > script.rb
require 'get_process_mem'
mem = GetProcessMem.new
before = mem.mb
require 'mail'
after = mem.mb
puts after - before
EOF
Results
$ env BUNDLE_GEMFILE=2.6.1/gemfile bundle exec ruby script.rb
# => 41.44140625 # mb
$ env BUNDLE_GEMFILE=2.5.4/gemfile bundle exec ruby script.rb
# => 11.41015625 # mb
EWAT
Mail 2.6.1 takes up almost 4 times more memory at Require time 0_o. Initial guess is that this has to do with the switch from treetop to ragel via @bpot
cc/@matthewd