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Add test parallelization to Rails 

Provides both a forked process and threaded parallelization options. To
use add `parallelize` to your test suite.

Takes a `workers` argument that controls how many times the process
is forked. For each process a new database will be created suffixed
with the worker number; test-database-0 and test-database-1
respectively.

If `ENV["PARALLEL_WORKERS"]` is set the workers argument will be ignored
and the environment variable will be used instead. This is useful for CI
environments, or other environments where you may need more workers than
you do for local testing.

If the number of workers is set to `1` or fewer, the tests will not be
parallelized.

The default parallelization method is to fork processes. If you'd like to
use threads instead you can pass `with: :threads` to the `parallelize`
method. Note the threaded parallelization does not create multiple
database and will not work with system tests at this time.

parallelize(workers: 2, with: :threads)

The threaded parallelization uses Minitest's parallel exector directly.
The processes paralleliztion uses a Ruby Drb server.

For parallelization via threads a setup hook and cleanup hook are
provided.

```
class ActiveSupport::TestCase
  parallelize_setup do |worker|
    # setup databases
  end

  parallelize_teardown do |worker|
    # cleanup database
  end

  parallelize(workers: 2)
end
```

[Eileen M. Uchitelle, Aaron Patterson]
This commit is contained in:
eileencodes 2017-12-20 16:59:41 -05:00
parent 23c5558f37
commit 26821d9b57
12 changed files with 415 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
activerecord/lib/active_record.rb
View File

@ -163,6 +163,7 @@ module ActiveRecord
"active_record/tasks/postgresql_database_tasks"
end
autoload :TestDatabases, "active_record/test_databases"
autoload :TestFixtures, "active_record/fixtures"
def self.eager_load!

5
activerecord/lib/active_record/fixtures.rb
View File

@ -874,6 +874,7 @@ module ActiveRecord
class_attribute :use_instantiated_fixtures, default: false # true, false, or :no_instances
class_attribute :pre_loaded_fixtures, default: false
class_attribute :config, default: ActiveRecord::Base
class_attribute :lock_threads, default: true
end
module ClassMethods
@ -973,7 +974,7 @@ module ActiveRecord
@fixture_connections = enlist_fixture_connections
@fixture_connections.each do |connection|
connection.begin_transaction joinable: false
connection.pool.lock_thread = true
connection.pool.lock_thread = true if lock_threads
end
# When connections are established in the future, begin a transaction too
@ -989,7 +990,7 @@ module ActiveRecord
if connection && !@fixture_connections.include?(connection)
connection.begin_transaction joinable: false
connection.pool.lock_thread = true
connection.pool.lock_thread = true if lock_threads
@fixture_connections << connection
end
end

38
activerecord/lib/active_record/test_databases.rb Normal file
View File

@ -0,0 +1,38 @@
# frozen_string_literal: true
require "active_support/testing/parallelization"
module ActiveRecord
module TestDatabases # :nodoc:
ActiveSupport::Testing::Parallelization.after_fork_hook do |i|
create_and_migrate(i, spec_name: Rails.env)
end
ActiveSupport::Testing::Parallelization.run_cleanup_hook do |i|
drop(i, spec_name: Rails.env)
end
def self.create_and_migrate(i, spec_name:)
old, ENV["VERBOSE"] = ENV["VERBOSE"], "false"
connection_spec = ActiveRecord::Base.configurations[spec_name]
connection_spec["database"] += "-#{i}"
ActiveRecord::Tasks::DatabaseTasks.create(connection_spec)
ActiveRecord::Base.establish_connection(connection_spec)
ActiveRecord::Tasks::DatabaseTasks.migrate
ensure
ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations[Rails.env])
ENV["VERBOSE"] = old
end
def self.drop(i, spec_name:)
old, ENV["VERBOSE"] = ENV["VERBOSE"], "false"
connection_spec = ActiveRecord::Base.configurations[spec_name]
ActiveRecord::Tasks::DatabaseTasks.drop(connection_spec)
ensure
ENV["VERBOSE"] = old
end
end
end

5
activesupport/CHANGELOG.md
View File

@ -1,2 +1,7 @@
* Adds parallel testing to Rails
Parallelize your test suite with forked processes or threads.
*Eileen M. Uchitelle*, *Aaron Patterson*
Please check [5-2-stable](https://github.com/rails/rails/blob/5-2-stable/activesupport/CHANGELOG.md) for previous changes.

86
activesupport/lib/active_support/test_case.rb
View File

@ -11,6 +11,7 @@ require "active_support/testing/isolation"
require "active_support/testing/constant_lookup"
require "active_support/testing/time_helpers"
require "active_support/testing/file_fixtures"
require "active_support/testing/parallelization"
module ActiveSupport
class TestCase < ::Minitest::Test
@ -39,6 +40,91 @@ module ActiveSupport
def test_order
ActiveSupport.test_order ||= :random
end
# Parallelizes the test suite.
#
# Takes a `workers` argument that controls how many times the process
# is forked. For each process a new database will be created suffixed
# with the worker number.
#
# test-database-0
# test-database-1
#
# If `ENV["PARALLEL_WORKERS"]` is set the workers argument will be ignored
# and the environment variable will be used instead. This is useful for CI
# environments, or other environments where you may need more workers than
# you do for local testing.
#
# If the number of workers is set to `1` or fewer, the tests will not be
# parallelized.
#
# The default parallelization method is to fork processes. If you'd like to
# use threads instead you can pass `with: :threads` to the `parallelize`
# method. Note the threaded parallelization does not create multiple
# database and will not work with system tests at this time.
#
# parallelize(workers: 2, with: :threads)
#
# The threaded parallelization uses Minitest's parallel exector directly.
# The processes paralleliztion uses a Ruby Drb server.
def parallelize(workers: 2, with: :processes)
workers = ENV["PARALLEL_WORKERS"].to_i if ENV["PARALLEL_WORKERS"]
return if workers <= 1
executor = case with
when :processes
Testing::Parallelization.new(workers)
when :threads
Minitest::Parallel::Executor.new(workers)
else
raise ArgumentError, "#{with} is not a supported parallelization exectutor."
end
self.lock_threads = false if defined?(self.lock_threads) && with == :threads
Minitest.parallel_executor = executor
parallelize_me!
end
# Set up hook for parallel testing. This can be used if you have multiple
# databases or any behavior that needs to be run after the process is forked
# but before the tests run.
#
# Note: this feature is not available with the threaded parallelization.
#
# In your +test_helper.rb+ add the following:
#
# class ActiveSupport::TestCase
# parallelize_setup do
# # create databases
# end
# end
def parallelize_setup(&block)
ActiveSupport::Testing::Parallelization.after_fork_hook do |worker|
yield worker
end
end
# Clean up hook for parallel testing. This can be used to drop databases
# if your app uses multiple write/read databases or other clean up before
# the tests finish. This runs before the forked process is closed.
#
# Note: this feature is not available with the threaded parallelization.
#
# In your +test_helper.rb+ add the following:
#
# class ActiveSupport::TestCase
# parallelize_teardown do
# # drop databases
# end
# end
def parallelize_teardown(&block)
ActiveSupport::Testing::Parallelization.run_cleanup_hook do |worker|
yield worker
end
end
end
alias_method :method_name, :name

102
activesupport/lib/active_support/testing/parallelization.rb Normal file
View File

@ -0,0 +1,102 @@
# frozen_string_literal: true
require "drb"
require "drb/unix"
module ActiveSupport
module Testing
class Parallelization # :nodoc:
class Server
include DRb::DRbUndumped
def initialize
@queue = Queue.new
end
def record(reporter, result)
reporter.synchronize do
reporter.record(result)
end
end
def <<(o)
@queue << o
end
def pop; @queue.pop; end
end
@after_fork_hooks = []
def self.after_fork_hook(&blk)
@after_fork_hooks << blk
end
def self.after_fork_hooks
@after_fork_hooks
end
@run_cleanup_hooks = []
def self.run_cleanup_hook(&blk)
@run_cleanup_hooks << blk
end
def self.run_cleanup_hooks
@run_cleanup_hooks
end
def initialize(queue_size)
@queue_size = queue_size
@queue = Server.new
@pool = []
@url = DRb.start_service("drbunix:", @queue).uri
end
def after_fork(worker)
self.class.after_fork_hooks.each do |cb|
cb.call(worker)
end
end
def run_cleanup(worker)
self.class.run_cleanup_hooks.each do |cb|
cb.call(worker)
end
end
def start
@pool = @queue_size.times.map do |worker|
fork do
DRb.stop_service
after_fork(worker)
queue = DRbObject.new_with_uri(@url)
while job = queue.pop
klass = job[0]
method = job[1]
reporter = job[2]
result = Minitest.run_one_method(klass, method)
queue.record(reporter, result)
end
run_cleanup(worker)
end
end
end
def <<(work)
@queue << work
end
def shutdown
@queue_size.times { @queue << nil }
@pool.each { |pid| Process.waitpid pid }
end
end
end
end

83
guides/source/testing.md
View File

@ -462,6 +462,89 @@ Rails options:
-c, --[no-]color Enable color in the output
```
Parallel Testing
----------------
Parallel testing allows you to parallelize your test suite. While forking processes is the
default method, threading is supported as well. Running tests in parallel reduces the time it
takes your entire test suite to run.
## Parallel testing with processes
The default parallelization method is to fork processes using Ruby's DRb system. The processes
are forked based on the number of workers provided. The default is 2, but can be changed by the
number passed to the parallelize method. Active Record automatically handles creating and
migrating a new database for each worker to use.
To enable parallelization add the following to your `test_helper.rb`:
```
class ActiveSupport::TestCase
parallelize(workers: 2)
end
```
The number of workers passed is the number of times the process will be forked. You may want to
parallelize your local test suite differently from your CI, so an environment variable is provided
to be able to easily change the number of workers a test run should use:
```
PARALLEL_WORKERS=15 bin/rails test
```
When parallelizing tests, Active Record automatically handles creating and migrating a database for each
process. The databases will be suffixed with the number corresponding to the worker. For example, if you
have 2 workers the tests will create `test-database-0` and `test-database-1` respectively.
If the number of workers passed is 1 or fewer the processes will not be forked and the tests will not
be parallelized and the tests will use the original `test-database` database.
Two hooks are provided, one runs when the process is forked, and one runs before the processes are closed.
These can be useful if your app uses multiple databases or perform other tasks that depend on the number of
workers.
The `parallelize_setup` method is called right after the processes are forked. The `parallelize_teardown` metod
is called right before the processes are closed.
```
class ActiveSupport::TestCase
parallelize_setup do |worker|
# setup databases
end
parallelize_teardown do |worker|
# cleanup database
end
parallelize(workers: 2)
end
```
These methods are not needed or available when using parallel testing with threads.
## Parallel testing with threads
If you prefer using threads or are using JRuby, a threaded parallelization option is provided. The threaded
parallelizer is backed by Minitest's `Parallel::Executor`.
To change the parallelization method to use threads over forks put the following in your `test_helper.rb`
```
class ActiveSupport::TestCase
parallelize(workers: 2, with: :threads)
end
```
Rails applications generated from JRuby will automatically include the `with: :threads` option.
The number of workers passed to `parallelize` determines the number of threads the tests will use. You may
want to parallelize your local test suite differently from your CI, so an environment variable is provided
to be able to easily change the number of workers a test run should use:
```
PARALLEL_WORKERS=15 bin/rails test
```
The Test Database
-----------------

7
railties/lib/rails/generators/rails/app/templates/test/test_helper.rb.tt
View File

@ -3,6 +3,13 @@ require_relative '../config/environment'
require 'rails/test_help'
class ActiveSupport::TestCase
# Run tests in parallel with specified workers
<% if defined?(JRUBY_VERSION) -%>
parallelize(workers: 2, with: :threads)
<%- else -%>
parallelize(workers: 2)
<% end -%>
<% unless options[:skip_active_record] -%>
# Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
fixtures :all

1
railties/lib/rails/test_help.rb
View File

@ -22,6 +22,7 @@ if defined?(ActiveRecord::Base)
module ActiveSupport
class TestCase
include ActiveRecord::TestDatabases
include ActiveRecord::TestFixtures
self.fixture_path = "#{Rails.root}/test/fixtures/"
self.file_fixture_path = fixture_path + "files"

82
railties/test/application/test_runner_test.rb
View File

@ -502,10 +502,10 @@ module ApplicationTests
end
def test_output_inline_by_default
create_test_file :models, "post", pass: false
create_test_file :models, "post", pass: false, print: false
output = run_test_command("test/models/post_test.rb")
expect = %r{Running:\n\nPostTest\nF\n\nFailure:\nPostTest#test_truth \[[^\]]+test/models/post_test.rb:6\]:\nwups!\n\nbin/rails test test/models/post_test.rb:4\n\n\n\n}
expect = %r{Running:\n\nF\n\nFailure:\nPostTest#test_truth \[[^\]]+test/models/post_test.rb:6\]:\nwups!\n\nbin/rails test test/models/post_test.rb:4\n\n\n\n}
assert_match expect, output
end
@ -523,6 +523,29 @@ module ApplicationTests
capture(:stderr) { run_test_command("test/models/post_test.rb --fail-fast", stderr: true) })
end
def test_run_in_parallel_with_processes
file_name = create_parallel_processes_test_file
output = run_test_command(file_name)
assert_match %r{Finished in.*\n2 runs, 2 assertions}, output
end
def test_run_in_parallel_with_threads
app_path("/test/test_helper.rb") do |file_name|
file = File.read(file_name)
file.sub!(/parallelize\(([^\)]*)\)/, "parallelize(\\1, with: :threads)")
puts file
File.write(file_name, file)
end
file_name = create_parallel_threads_test_file
output = run_test_command(file_name)
assert_match %r{Finished in.*\n2 runs, 2 assertions}, output
end
def test_raise_error_when_specified_file_does_not_exist
error = capture(:stderr) { run_test_command("test/not_exists.rb", stderr: true) }
assert_match(%r{cannot load such file.+test/not_exists\.rb}, error)
@ -800,19 +823,70 @@ module ApplicationTests
RUBY
end
def create_test_file(path = :unit, name = "test", pass: true)
def create_test_file(path = :unit, name = "test", pass: true, print: true)
app_file "test/#{path}/#{name}_test.rb", <<-RUBY
require 'test_helper'
class #{name.camelize}Test < ActiveSupport::TestCase
def test_truth
puts "#{name.camelize}Test"
puts "#{name.camelize}Test" if #{print}
assert #{pass}, 'wups!'
end
end
RUBY
end
def create_parallel_processes_test_file
app_file "test/models/parallel_test.rb", <<-RUBY
require 'test_helper'
class ParallelTest < ActiveSupport::TestCase
RD1, WR1 = IO.pipe
RD2, WR2 = IO.pipe
test "one" do
WR1.close
assert_equal "x", RD1.read(1) # blocks until two runs
RD2.close
WR2.write "y" # Allow two to run
WR2.close
end
test "two" do
RD1.close
WR1.write "x" # Allow one to run
WR1.close
WR2.close
assert_equal "y", RD2.read(1) # blocks until one runs
end
end
RUBY
end
def create_parallel_threads_test_file
app_file "test/models/parallel_test.rb", <<-RUBY
require 'test_helper'
class ParallelTest < ActiveSupport::TestCase
Q1 = Queue.new
Q2 = Queue.new
test "one" do
assert_equal "x", Q1.pop # blocks until two runs
Q2 << "y"
end
test "two" do
Q1 << "x"
assert_equal "y", Q2.pop # blocks until one runs
end
end
RUBY
end
def create_env_test
app_file "test/unit/env_test.rb", <<-RUBY
require 'test_helper'

5
railties/test/application/test_test.rb
View File

@ -7,10 +7,15 @@ module ApplicationTests
include ActiveSupport::Testing::Isolation
def setup
@old = ENV["PARALLEL_WORKERS"]
ENV["PARALLEL_WORKERS"] = "0"
build_app
end
def teardown
ENV["PARALLEL_WORKERS"] = @old
teardown_app
end

7
railties/test/isolation/abstract_unit.rb
View File

@ -38,7 +38,12 @@ module TestHelpers
end
def app_path(*args)
tmp_path(*%w[app] + args)
path = tmp_path(*%w[app] + args)
if block_given?
yield path
else
path
end
end
def framework_path