Remove AtExit code

CHANGELOG.md

@@ -1,5 +1,11 @@
 ## Current
 
+concurrent-ruby:
+
+* Concurrent.disable_at_exit_handlers! is no longer needed and was deprecated.
+* AbstractExecutorService#auto_terminate= was deprecated and has no effect. 
+  Set :auto_terminate option instead when executor is initialized.
+
 ## Release v1.1.6.pre1, edge v0.6.0.pre1 (26 Jan 2020)
 
 concurrent-ruby:

lib/concurrent-ruby-edge/concurrent/channel.rb

@@ -15,7 +15,7 @@ class Channel
     include Enumerable
 
     # NOTE: Move to global IO pool once stable
-    GOROUTINES = Concurrent::CachedThreadPool.new(auto_terminate: true)
+    GOROUTINES = Concurrent::CachedThreadPool.new
     private_constant :GOROUTINES
 
     BUFFER_TYPES = {

lib/concurrent-ruby/concurrent/configuration.rb

@@ -3,13 +3,14 @@
 require 'concurrent/errors'
 require 'concurrent/atomic/atomic_reference'
 require 'concurrent/concern/logging'
+require 'concurrent/concern/deprecation'
 require 'concurrent/executor/immediate_executor'
 require 'concurrent/executor/cached_thread_pool'
-require 'concurrent/utility/at_exit'
 require 'concurrent/utility/processor_counter'
 
 module Concurrent
   extend Concern::Logging
+  extend Concern::Deprecation
 
   autoload :Options, 'concurrent/options'
   autoload :TimerSet, 'concurrent/executor/timer_set'
@@ -97,15 +98,15 @@ def self.global_logger=(value)
   end
 
   # @!visibility private
-  GLOBAL_FAST_EXECUTOR = Delay.new { Concurrent.new_fast_executor(auto_terminate: true) }
+  GLOBAL_FAST_EXECUTOR = Delay.new { Concurrent.new_fast_executor }
   private_constant :GLOBAL_FAST_EXECUTOR
 
   # @!visibility private
-  GLOBAL_IO_EXECUTOR = Delay.new { Concurrent.new_io_executor(auto_terminate: true) }
+  GLOBAL_IO_EXECUTOR = Delay.new { Concurrent.new_io_executor }
   private_constant :GLOBAL_IO_EXECUTOR
 
   # @!visibility private
-  GLOBAL_TIMER_SET = Delay.new { TimerSet.new(auto_terminate: true) }
+  GLOBAL_TIMER_SET = Delay.new { TimerSet.new }
   private_constant :GLOBAL_TIMER_SET
 
   # @!visibility private
@@ -125,9 +126,10 @@ def self.global_logger=(value)
   # @note This method should *never* be called
   #   from within a gem. It should *only* be used from within the main
   #   application and even then it should be used only when necessary.
+  # @deprecated Has no effect since it is no longer needed, see https://github.com/ruby-concurrency/concurrent-ruby/pull/841.
   #
   def self.disable_at_exit_handlers!
-    AT_EXIT.enabled = false
+    deprecated "Method #disable_at_exit_handlers! has no effect since it is no longer needed, see https://github.com/ruby-concurrency/concurrent-ruby/pull/841."
   end
 
   # Global thread pool optimized for short, fast *operations*.

lib/concurrent-ruby/concurrent/executor/abstract_executor_service.rb

@@ -1,14 +1,15 @@
 require 'concurrent/errors'
+require 'concurrent/concern/deprecation'
 require 'concurrent/executor/executor_service'
 require 'concurrent/synchronization'
-require 'concurrent/utility/at_exit'
 
 module Concurrent
 
   # @!macro abstract_executor_service_public_api
   # @!visibility private
   class AbstractExecutorService < Synchronization::LockableObject
     include ExecutorService
+    include Concern::Deprecation
 
     # The set of possible fallback policies that may be set at thread pool creation.
     FALLBACK_POLICIES = [:abort, :discard, :caller_runs].freeze
@@ -22,8 +23,9 @@ class AbstractExecutorService < Synchronization::LockableObject
     def initialize(opts = {}, &block)
       super(&nil)
       synchronize do
-        ns_initialize(opts, &block)
+        @auto_terminate = opts.fetch(:auto_terminate, true)
         @name = opts.fetch(:name) if opts.key?(:name)
+        ns_initialize(opts, &block)
       end
     end
 
@@ -63,12 +65,12 @@ def shutdown?
 
     # @!macro executor_service_method_auto_terminate_question
     def auto_terminate?
-      synchronize { ns_auto_terminate? }
+      synchronize { @auto_terminate }
     end
 
     # @!macro executor_service_method_auto_terminate_setter
     def auto_terminate=(value)
-      synchronize { self.ns_auto_terminate = value }
+      deprecated "Method #auto_terminate= has no effect. Set :auto_terminate option when executor is initialized."
     end
 
     private
@@ -119,25 +121,8 @@ def ns_kill_execution
     end
 
     def ns_auto_terminate?
-      !!@auto_terminate
+      @auto_terminate
     end
 
-    def ns_auto_terminate=(value)
-      case value
-      when true
-        AT_EXIT.add(self) { terminate_at_exit }
-        @auto_terminate = true
-      when false
-        AT_EXIT.delete(self)
-        @auto_terminate = false
-      else
-        raise ArgumentError
-      end
-    end
-
-    def terminate_at_exit
-      kill # TODO be gentle first
-      wait_for_termination(10)
-    end
   end
 end

lib/concurrent-ruby/concurrent/executor/cached_thread_pool.rb

@@ -51,10 +51,9 @@ def initialize(opts = {})
     def ns_initialize(opts)
       super(opts)
       if Concurrent.on_jruby?
-        self.auto_terminate = opts.fetch(:auto_terminate, true)
         @max_queue          = 0
         @executor           = java.util.concurrent.Executors.newCachedThreadPool(
-            DaemonThreadFactory.new(self.auto_terminate?))
+            DaemonThreadFactory.new(ns_auto_terminate?))
         @executor.setRejectedExecutionHandler(FALLBACK_POLICY_CLASSES[@fallback_policy].new)
         @executor.setKeepAliveTime(opts.fetch(:idletime, DEFAULT_THREAD_IDLETIMEOUT), java.util.concurrent.TimeUnit::SECONDS)
       end

lib/concurrent-ruby/concurrent/executor/executor_service.rb

@@ -111,10 +111,10 @@ module Concurrent
 
   # @!macro executor_service_method_auto_terminate_setter
   #
-  #   Set the auto-terminate behavior for this executor.
   #
+  #   Set the auto-terminate behavior for this executor.
+  #   @deprecated Has no effect
   #   @param [Boolean] value The new auto-terminate value to set for this executor.
-  #
   #   @return [Boolean] `true` when auto-termination is enabled else `false`.
 
   ###################################################################

lib/concurrent-ruby/concurrent/executor/fixed_thread_pool.rb

@@ -121,9 +121,7 @@ module Concurrent
   #   * `max_queue`: The maximum number of tasks that may be waiting in the work queue at
   #     any one time. When the queue size reaches `max_queue` and no new threads can be created,
   #     subsequent tasks will be rejected in accordance with the configured `fallback_policy`.
-  #   * `auto_terminate`: When true (default) an `at_exit` handler will be registered which
-  #     will stop the thread pool when the application exits. See below for more information
-  #     on shutting down thread pools.
+  #   * `auto_terminate`: When true (default), the threads started will be marked as daemon.
   #   * `fallback_policy`: The policy defining how rejected tasks are handled.
   #
   #   Three fallback policies are supported:
@@ -148,16 +146,12 @@ module Concurrent
   #
   #   On some runtime platforms (most notably the JVM) the application will not
   #   exit until all thread pools have been shutdown. To prevent applications from
-  #   "hanging" on exit all thread pools include an `at_exit` handler that will
-  #   stop the thread pool when the application exits. This handler uses a brute
-  #   force method to stop the pool and makes no guarantees regarding resources being
-  #   used by any tasks still running. Registration of this `at_exit` handler can be
-  #   prevented by setting the thread pool's constructor `:auto_terminate` option to
-  #   `false` when the thread pool is created. All thread pools support this option.
+  #   "hanging" on exit, all threads can be marked as daemon according to the
+  #   `:auto_terminate` option.
   #
   #   ```ruby
-  #   pool1 = Concurrent::FixedThreadPool.new(5) # an `at_exit` handler will be registered
-  #   pool2 = Concurrent::FixedThreadPool.new(5, auto_terminate: false) # prevent `at_exit` handler registration
+  #   pool1 = Concurrent::FixedThreadPool.new(5) # threads will be marked as daemon
+  #   pool2 = Concurrent::FixedThreadPool.new(5, auto_terminate: false) # mark threads as non-daemon
   #   ```
   #
   #   @note Failure to properly shutdown a thread pool can lead to unpredictable results.
@@ -166,7 +160,7 @@ module Concurrent
   #   @see http://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html Java Tutorials: Thread Pools
   #   @see http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Executors.html Java Executors class
   #   @see http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html Java ExecutorService interface
-  #   @see http://ruby-doc.org//core-2.2.0/Kernel.html#method-i-at_exit Kernel#at_exit
+  #   @see https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html#setDaemon-boolean-
 
 
 

lib/concurrent-ruby/concurrent/executor/java_executor_service.rb

@@ -38,15 +38,13 @@ def wait_for_termination(timeout = nil)
 
       def shutdown
         synchronize do
-          self.ns_auto_terminate = false
           @executor.shutdown
           nil
         end
       end
 
       def kill
         synchronize do
-          self.ns_auto_terminate = false
           @executor.shutdownNow
           nil
         end
@@ -83,5 +81,23 @@ def run
       end
       private_constant :Job
     end
+
+    class DaemonThreadFactory
+      # hide include from YARD
+      send :include, java.util.concurrent.ThreadFactory
+
+      def initialize(daemonize = true)
+        @daemonize = daemonize
+      end
+
+      def newThread(runnable)
+        thread = java.util.concurrent.Executors.defaultThreadFactory().newThread(runnable)
+        thread.setDaemon(@daemonize)
+        return thread
+      end
+    end
+
+    private_constant :DaemonThreadFactory
+
   end
 end

lib/concurrent-ruby/concurrent/executor/java_single_thread_executor.rb

@@ -17,12 +17,13 @@ def initialize(opts = {})
       end
 
       private
-      
+
       def ns_initialize(opts)
-        @executor = java.util.concurrent.Executors.newSingleThreadExecutor
+        @executor = java.util.concurrent.Executors.newSingleThreadExecutor(
+            DaemonThreadFactory.new(ns_auto_terminate?)
+        )
         @fallback_policy = opts.fetch(:fallback_policy, :discard)
         raise ArgumentError.new("#{@fallback_policy} is not a valid fallback policy") unless FALLBACK_POLICY_CLASSES.keys.include?(@fallback_policy)
-        self.auto_terminate = opts.fetch(:auto_terminate, true)
       end
     end
   end

lib/concurrent-ruby/concurrent/executor/java_thread_pool_executor.rb

@@ -116,27 +116,11 @@ def ns_initialize(opts)
             idletime,
             java.util.concurrent.TimeUnit::SECONDS,
             queue,
-            DaemonThreadFactory.new(self.auto_terminate?),
+            DaemonThreadFactory.new(ns_auto_terminate?),
             FALLBACK_POLICY_CLASSES[@fallback_policy].new)
 
       end
     end
 
-    class DaemonThreadFactory
-      # hide include from YARD
-      send :include, java.util.concurrent.ThreadFactory
-
-      def initialize(daemonize = true)
-        @daemonize = daemonize
-      end
-
-      def newThread(runnable)
-        thread = java.util.concurrent.Executors.defaultThreadFactory().newThread(runnable)
-        thread.setDaemon(@daemonize)
-        return thread
-      end
-    end
-
-    private_constant :DaemonThreadFactory
   end
 end

lib/concurrent-ruby/concurrent/executor/ruby_executor_service.rb

@@ -27,7 +27,6 @@ def post(*args, &task)
     def shutdown
       synchronize do
         break unless running?
-        self.ns_auto_terminate = false
         stop_event.set
         ns_shutdown_execution
       end
@@ -37,7 +36,6 @@ def shutdown
     def kill
       synchronize do
         break if shutdown?
-        self.ns_auto_terminate = false
         stop_event.set
         ns_kill_execution
         stopped_event.set

lib/concurrent-ruby/concurrent/executor/ruby_single_thread_executor.rb

@@ -15,7 +15,6 @@ def initialize(opts = {})
         max_queue: 0,
         idletime: DEFAULT_THREAD_IDLETIMEOUT,
         fallback_policy: opts.fetch(:fallback_policy, :discard),
-        auto_terminate: opts.fetch(:auto_terminate, true)
       )
     end
   end

lib/concurrent-ruby/concurrent/executor/ruby_thread_pool_executor.rb

@@ -122,8 +122,6 @@ def ns_initialize(opts)
       raise ArgumentError.new("`min_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if @min_length < DEFAULT_MIN_POOL_SIZE
       raise ArgumentError.new("`min_threads` cannot be more than `max_threads`") if min_length > max_length
 
-      self.auto_terminate = opts.fetch(:auto_terminate, true)
-
       @pool                 = [] # all workers
       @ready                = [] # used as a stash (most idle worker is at the start)
       @queue                = [] # used as queue

lib/concurrent-ruby/concurrent/executor/timer_set.rb

@@ -77,7 +77,6 @@ def ns_initialize(opts)
       @timer_executor     = SingleThreadExecutor.new
       @condition          = Event.new
       @ruby_pid           = $$ # detects if Ruby has forked
-      self.auto_terminate = opts.fetch(:auto_terminate, true)
     end
 
     # Post the task to the internal queue.