* Add request pool to improve delivery performance Fix #7909 * Ensure connection is closed when exception interrupts execution * Remove Timeout#timeout from socket connection * Fix infinite retrial loop on HTTP::ConnectionError * Close sockets on failure, reduce idle time to 90 seconds * Add MAX_REQUEST_POOL_SIZE option to limit concurrent connections to the same server * Use a shared pool size, 512 by default, to stay below open file limit * Add some tests * Add more tests * Reduce MAX_IDLE_TIME from 90 to 30 seconds, reap every 30 seconds * Use a shared pool that returns preferred connection but re-purposes other ones when needed * Fix wrong connection being returned on subsequent calls within the same thread * Reduce mutex calls on flushes from 2 to 1 and add test for reapingpull/4/head
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# frozen_string_literal: true | |||
require 'connection_pool' | |||
require_relative './shared_timed_stack' | |||
class ConnectionPool::SharedConnectionPool < ConnectionPool | |||
def initialize(options = {}, &block) | |||
super(options, &block) | |||
@available = ConnectionPool::SharedTimedStack.new(@size, &block) | |||
end | |||
delegate :size, :flush, to: :@available | |||
def with(preferred_tag, options = {}) | |||
Thread.handle_interrupt(Exception => :never) do | |||
conn = checkout(preferred_tag, options) | |||
begin | |||
Thread.handle_interrupt(Exception => :immediate) do | |||
yield conn | |||
end | |||
ensure | |||
checkin(preferred_tag) | |||
end | |||
end | |||
end | |||
def checkout(preferred_tag, options = {}) | |||
if ::Thread.current[key(preferred_tag)] | |||
::Thread.current[key_count(preferred_tag)] += 1 | |||
::Thread.current[key(preferred_tag)] | |||
else | |||
::Thread.current[key_count(preferred_tag)] = 1 | |||
::Thread.current[key(preferred_tag)] = @available.pop(preferred_tag, options[:timeout] || @timeout) | |||
end | |||
end | |||
def checkin(preferred_tag) | |||
if ::Thread.current[key(preferred_tag)] | |||
if ::Thread.current[key_count(preferred_tag)] == 1 | |||
@available.push(::Thread.current[key(preferred_tag)]) | |||
::Thread.current[key(preferred_tag)] = nil | |||
else | |||
::Thread.current[key_count(preferred_tag)] -= 1 | |||
end | |||
else | |||
raise ConnectionPool::Error, 'no connections are checked out' | |||
end | |||
nil | |||
end | |||
private | |||
def key(tag) | |||
:"#{@key}-#{tag}" | |||
end | |||
def key_count(tag) | |||
:"#{@key_count}-#{tag}" | |||
end | |||
end |
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# frozen_string_literal: true | |||
class ConnectionPool::SharedTimedStack | |||
def initialize(max = 0, &block) | |||
@create_block = block | |||
@max = max | |||
@created = 0 | |||
@queue = [] | |||
@tagged_queue = Hash.new { |hash, key| hash[key] = [] } | |||
@mutex = Mutex.new | |||
@resource = ConditionVariable.new | |||
end | |||
def push(connection) | |||
@mutex.synchronize do | |||
store_connection(connection) | |||
@resource.broadcast | |||
end | |||
end | |||
alias << push | |||
def pop(preferred_tag, timeout = 5.0) | |||
deadline = current_time + timeout | |||
@mutex.synchronize do | |||
loop do | |||
return fetch_preferred_connection(preferred_tag) unless @tagged_queue[preferred_tag].empty? | |||
connection = try_create(preferred_tag) | |||
return connection if connection | |||
to_wait = deadline - current_time | |||
raise Timeout::Error, "Waited #{timeout} sec" if to_wait <= 0 | |||
@resource.wait(@mutex, to_wait) | |||
end | |||
end | |||
end | |||
def empty? | |||
size.zero? | |||
end | |||
def size | |||
@mutex.synchronize do | |||
@queue.size | |||
end | |||
end | |||
def flush | |||
@mutex.synchronize do | |||
@queue.delete_if do |connection| | |||
delete = !connection.in_use && (connection.dead || connection.seconds_idle >= RequestPool::MAX_IDLE_TIME) | |||
if delete | |||
@tagged_queue[connection.site].delete(connection) | |||
connection.close | |||
@created -= 1 | |||
end | |||
delete | |||
end | |||
end | |||
end | |||
private | |||
def try_create(preferred_tag) | |||
if @created == @max && !@queue.empty? | |||
throw_away_connection = @queue.pop | |||
@tagged_queue[throw_away_connection.site].delete(throw_away_connection) | |||
@create_block.call(preferred_tag) | |||
elsif @created != @max | |||
connection = @create_block.call(preferred_tag) | |||
@created += 1 | |||
connection | |||
end | |||
end | |||
def fetch_preferred_connection(preferred_tag) | |||
connection = @tagged_queue[preferred_tag].pop | |||
@queue.delete(connection) | |||
connection | |||
end | |||
def current_time | |||
Process.clock_gettime(Process::CLOCK_MONOTONIC) | |||
end | |||
def store_connection(connection) | |||
@tagged_queue[connection.site].push(connection) | |||
@queue.push(connection) | |||
end | |||
end |
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# frozen_string_literal: true | |||
require_relative './connection_pool/shared_connection_pool' | |||
class RequestPool | |||
def self.current | |||
@current ||= RequestPool.new | |||
end | |||
class Reaper | |||
attr_reader :pool, :frequency | |||
def initialize(pool, frequency) | |||
@pool = pool | |||
@frequency = frequency | |||
end | |||
def run | |||
return unless frequency&.positive? | |||
Thread.new(frequency, pool) do |t, p| | |||
loop do | |||
sleep t | |||
p.flush | |||
end | |||
end | |||
end | |||
end | |||
MAX_IDLE_TIME = 30 | |||
WAIT_TIMEOUT = 5 | |||
MAX_POOL_SIZE = ENV.fetch('MAX_REQUEST_POOL_SIZE', 512).to_i | |||
class Connection | |||
attr_reader :site, :last_used_at, :created_at, :in_use, :dead, :fresh | |||
def initialize(site) | |||
@site = site | |||
@http_client = http_client | |||
@last_used_at = nil | |||
@created_at = current_time | |||
@dead = false | |||
@fresh = true | |||
end | |||
def use | |||
@last_used_at = current_time | |||
@in_use = true | |||
retries = 0 | |||
begin | |||
yield @http_client | |||
rescue HTTP::ConnectionError | |||
# It's possible the connection was closed, so let's | |||
# try re-opening it once | |||
close | |||
if @fresh || retries.positive? | |||
raise | |||
else | |||
@http_client = http_client | |||
retries += 1 | |||
retry | |||
end | |||
rescue StandardError | |||
# If this connection raises errors of any kind, it's | |||
# better if it gets reaped as soon as possible | |||
close | |||
@dead = true | |||
raise | |||
end | |||
ensure | |||
@fresh = false | |||
@in_use = false | |||
end | |||
def seconds_idle | |||
current_time - (@last_used_at || @created_at) | |||
end | |||
def close | |||
@http_client.close | |||
end | |||
private | |||
def http_client | |||
Request.http_client.persistent(@site, timeout: MAX_IDLE_TIME) | |||
end | |||
def current_time | |||
Process.clock_gettime(Process::CLOCK_MONOTONIC) | |||
end | |||
end | |||
def initialize | |||
@pool = ConnectionPool::SharedConnectionPool.new(size: MAX_POOL_SIZE, timeout: WAIT_TIMEOUT) { |site| Connection.new(site) } | |||
@reaper = Reaper.new(self, 30) | |||
@reaper.run | |||
end | |||
def with(site, &block) | |||
@pool.with(site) do |connection| | |||
ActiveSupport::Notifications.instrument('with.request_pool', miss: connection.fresh, host: connection.site) do | |||
connection.use(&block) | |||
end | |||
end | |||
end | |||
delegate :size, :flush, to: :@pool | |||
end |
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# frozen_string_literal: true | |||
require 'rails_helper' | |||
describe ConnectionPool::SharedConnectionPool do | |||
class MiniConnection | |||
attr_reader :site | |||
def initialize(site) | |||
@site = site | |||
end | |||
end | |||
subject { described_class.new(size: 5, timeout: 5) { |site| MiniConnection.new(site) } } | |||
describe '#with' do | |||
it 'runs a block with a connection' do | |||
block_run = false | |||
subject.with('foo') do |connection| | |||
expect(connection).to be_a MiniConnection | |||
block_run = true | |||
end | |||
expect(block_run).to be true | |||
end | |||
end | |||
end |
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# frozen_string_literal: true | |||
require 'rails_helper' | |||
describe ConnectionPool::SharedTimedStack do | |||
class MiniConnection | |||
attr_reader :site | |||
def initialize(site) | |||
@site = site | |||
end | |||
end | |||
subject { described_class.new(5) { |site| MiniConnection.new(site) } } | |||
describe '#push' do | |||
it 'keeps the connection in the stack' do | |||
subject.push(MiniConnection.new('foo')) | |||
expect(subject.size).to eq 1 | |||
end | |||
end | |||
describe '#pop' do | |||
it 'returns a connection' do | |||
expect(subject.pop('foo')).to be_a MiniConnection | |||
end | |||
it 'returns the same connection that was pushed in' do | |||
connection = MiniConnection.new('foo') | |||
subject.push(connection) | |||
expect(subject.pop('foo')).to be connection | |||
end | |||
it 'does not create more than maximum amount of connections' do | |||
expect { 6.times { subject.pop('foo', 0) } }.to raise_error Timeout::Error | |||
end | |||
it 'repurposes a connection for a different site when maximum amount is reached' do | |||
5.times { subject.push(MiniConnection.new('foo')) } | |||
expect(subject.pop('bar')).to be_a MiniConnection | |||
end | |||
end | |||
describe '#empty?' do | |||
it 'returns true when no connections on the stack' do | |||
expect(subject.empty?).to be true | |||
end | |||
it 'returns false when there are connections on the stack' do | |||
subject.push(MiniConnection.new('foo')) | |||
expect(subject.empty?).to be false | |||
end | |||
end | |||
describe '#size' do | |||
it 'returns the number of connections on the stack' do | |||
2.times { subject.push(MiniConnection.new('foo')) } | |||
expect(subject.size).to eq 2 | |||
end | |||
end | |||
end |
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# frozen_string_literal: true | |||
require 'rails_helper' | |||
describe RequestPool do | |||
subject { described_class.new } | |||
describe '#with' do | |||
it 'returns a HTTP client for a host' do | |||
subject.with('http://example.com') do |http_client| | |||
expect(http_client).to be_a HTTP::Client | |||
end | |||
end | |||
it 'returns the same instance of HTTP client within the same thread for the same host' do | |||
test_client = nil | |||
subject.with('http://example.com') { |http_client| test_client = http_client } | |||
expect(test_client).to_not be_nil | |||
subject.with('http://example.com') { |http_client| expect(http_client).to be test_client } | |||
end | |||
it 'returns different HTTP clients for different hosts' do | |||
test_client = nil | |||
subject.with('http://example.com') { |http_client| test_client = http_client } | |||
expect(test_client).to_not be_nil | |||
subject.with('http://example.org') { |http_client| expect(http_client).to_not be test_client } | |||
end | |||
it 'grows to the number of threads accessing it' do | |||
stub_request(:get, 'http://example.com/').to_return(status: 200, body: 'Hello!') | |||
subject | |||
threads = 20.times.map do |i| | |||
Thread.new do | |||
20.times do | |||
subject.with('http://example.com') do |http_client| | |||
http_client.get('/').flush | |||
end | |||
end | |||
end | |||
end | |||
threads.map(&:join) | |||
expect(subject.size).to be > 1 | |||
end | |||
it 'closes idle connections' do | |||
stub_request(:get, 'http://example.com/').to_return(status: 200, body: 'Hello!') | |||
subject.with('http://example.com') do |http_client| | |||
http_client.get('/').flush | |||
end | |||
expect(subject.size).to eq 1 | |||
sleep RequestPool::MAX_IDLE_TIME + 30 + 1 | |||
expect(subject.size).to eq 0 | |||
end | |||
end | |||
end |