Increase connection pool to allow for up to 70% speed increase on bundle install

bundler/lib/bundler/fetcher/gem_remote_fetcher.rb

@@ -5,6 +5,12 @@
 module Bundler
   class Fetcher
     class GemRemoteFetcher < Gem::RemoteFetcher
+      def initialize(*)
+        super
+
+        @pool_size = 5
+      end
+
       def request(*args)
         super do |req|
           req.delete("User-Agent") if headers["User-Agent"]

bundler/spec/bundler/fetcher/gem_remote_fetcher_spec.rb

@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require "rubygems/remote_fetcher"
+require "bundler/fetcher/gem_remote_fetcher"
+require_relative "../../support/artifice/helpers/artifice"
+require "bundler/vendored_persistent.rb"
+
+RSpec.describe Bundler::Fetcher::GemRemoteFetcher do
+  describe "Parallel download" do
+    it "download using multiple connections from the pool" do
+      unless Bundler.rubygems.provides?(">= 4.0.0.dev")
+        skip "This example can only run when RubyGems supports multiple http connection pool"
+      end
+
+      require_relative "../../support/artifice/helpers/endpoint"
+      concurrent_ruby_path = Dir[scoped_base_system_gem_path.join("gems/concurrent-ruby-*/lib/concurrent-ruby")].first
+      $LOAD_PATH.unshift(concurrent_ruby_path)
+      require "concurrent-ruby"
+
+      require_rack_test
+      responses = []
+
+      latch1 = Concurrent::CountDownLatch.new
+      latch2 = Concurrent::CountDownLatch.new
+      previous_client = Gem::Request::ConnectionPools.client
+      dummy_endpoint = Class.new(Endpoint) do
+        get "/foo" do
+          latch2.count_down
+          latch1.wait
+
+          responses << "foo"
+        end
+
+        get "/bar" do
+          responses << "bar"
+
+          latch1.count_down
+        end
+      end
+
+      Artifice.activate_with(dummy_endpoint)
+      Gem::Request::ConnectionPools.client = Gem::Net::HTTP
+
+      first_request = Thread.new do
+        subject.fetch_path("https://example.org/foo")
+      end
+      second_request = Thread.new do
+        latch2.wait
+        subject.fetch_path("https://example.org/bar")
+      end
+
+      [first_request, second_request].each(&:join)
+
+      expect(responses).to eq(["bar", "foo"])
+    ensure
+      Artifice.deactivate
+      Gem::Request::ConnectionPools.client = previous_client
+    end
+  end
+end

lib/rubygems/remote_fetcher.rb

@@ -82,6 +82,7 @@ def initialize(proxy = nil, dns = nil, headers = {})
     @proxy = proxy
     @pools = {}
     @pool_lock = Thread::Mutex.new
+    @pool_size = 1
     @cert_files = Gem::Request.get_cert_files
 
     @headers = headers
@@ -338,7 +339,7 @@ def proxy_for(proxy, uri)
 
   def pools_for(proxy)
     @pool_lock.synchronize do
-      @pools[proxy] ||= Gem::Request::ConnectionPools.new proxy, @cert_files
+      @pools[proxy] ||= Gem::Request::ConnectionPools.new proxy, @cert_files, @pool_size
     end
   end
 end

lib/rubygems/request/connection_pools.rb

@@ -7,11 +7,12 @@ class << self
     attr_accessor :client
   end
 
-  def initialize(proxy_uri, cert_files)
+  def initialize(proxy_uri, cert_files, pool_size = 1)
     @proxy_uri  = proxy_uri
     @cert_files = cert_files
     @pools      = {}
     @pool_mutex = Thread::Mutex.new
+    @pool_size  = pool_size
   end
 
   def pool_for(uri)
@@ -20,9 +21,9 @@ def pool_for(uri)
     @pool_mutex.synchronize do
       @pools[key] ||=
         if https? uri
-          Gem::Request::HTTPSPool.new(http_args, @cert_files, @proxy_uri)
+          Gem::Request::HTTPSPool.new(http_args, @cert_files, @proxy_uri, @pool_size)
         else
-          Gem::Request::HTTPPool.new(http_args, @cert_files, @proxy_uri)
+          Gem::Request::HTTPPool.new(http_args, @cert_files, @proxy_uri, @pool_size)
         end
     end
   end

lib/rubygems/request/http_pool.rb

@@ -9,12 +9,14 @@
 class Gem::Request::HTTPPool # :nodoc:
   attr_reader :cert_files, :proxy_uri
 
-  def initialize(http_args, cert_files, proxy_uri)
+  def initialize(http_args, cert_files, proxy_uri, pool_size)
     @http_args  = http_args
     @cert_files = cert_files
     @proxy_uri  = proxy_uri
-    @queue      = Thread::SizedQueue.new 1
-    @queue << nil
+    @pool_size  = pool_size
+
+    @queue      = Thread::SizedQueue.new @pool_size
+    setup_queue
   end
 
   def checkout
@@ -31,7 +33,8 @@ def close_all
         connection.finish
       end
     end
-    @queue.push(nil)
+
+    setup_queue
   end
 
   private
@@ -44,4 +47,8 @@ def setup_connection(connection)
     connection.start
     connection
   end
+
+  def setup_queue
+    @pool_size.times { @queue.push(nil) }
+  end
 end

test/rubygems/test_gem_request_connection_pools.rb

@@ -148,4 +148,16 @@ def test_thread_waits_for_connection
       end
     end.join
   end
+
+  def test_checkouts_multiple_connections_from_the_pool
+    uri = Gem::URI.parse("http://example/some_endpoint")
+    pools = Gem::Request::ConnectionPools.new nil, [], 2
+    pool  = pools.pool_for uri
+
+    pool.checkout
+
+    Thread.new do
+      assert_not_nil(pool.checkout)
+    end.join
+  end
 end

tool/bundler/test_gems.rb

@@ -11,6 +11,7 @@
 gem "rb_sys"
 gem "fiddle"
 gem "rubygems-generate_index", "~> 1.1"
+gem "concurrent-ruby"
 gem "psych"
 gem "etc", platforms: [:ruby, :windows]
 gem "open3"

tool/bundler/test_gems.rb.lock

@@ -4,6 +4,7 @@ GEM
     base64 (0.3.0)
     builder (3.3.0)
     compact_index (0.15.0)
+    concurrent-ruby (1.3.5)
     date (3.5.0)
     date (3.5.0-java)
     etc (1.4.6)
@@ -59,6 +60,7 @@ PLATFORMS
 DEPENDENCIES
   builder (~> 3.2)
   compact_index (~> 0.15.0)
+  concurrent-ruby
   etc
   fiddle
   open3
@@ -75,6 +77,7 @@ CHECKSUMS
   base64 (0.3.0) sha256=27337aeabad6ffae05c265c450490628ef3ebd4b67be58257393227588f5a97b
   builder (3.3.0) sha256=497918d2f9dca528fdca4b88d84e4ef4387256d984b8154e9d5d3fe5a9c8835f
   compact_index (0.15.0) sha256=5c6c404afca8928a7d9f4dde9524f6e1610db17e675330803055db282da84a8b
+  concurrent-ruby (1.3.5) sha256=813b3e37aca6df2a21a3b9f1d497f8cbab24a2b94cab325bffe65ee0f6cbebc6
   date (3.5.0) sha256=5e74fd6c04b0e65d97ad4f3bb5cb2d8efb37f386cc848f46310b4593ffc46ee5
   date (3.5.0-java) sha256=d6876651299185b935e1b834a353e3a1d1db054be478967e8104e30a9a8f1127
   etc (1.4.6) sha256=0f7e9e7842ea5e3c3bd9bc81746ebb8c65ea29e4c42a93520a0d638129c7de01