Merge pull request #8258 from Homebrew/dependabot/bundler/Library/Hom…

…ebrew/concurrent-ruby-1.1.7 build(deps): bump concurrent-ruby from 1.1.6 to 1.1.7 in /Library/Homebrew
Homebrew · Aug 10, 2020 · e72275e · e72275e
2 parents 283583c + 48dd758
commit e72275e
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Showing 124 changed files with 122 additions and 86 deletions.
diff --git a/Library/Homebrew/Gemfile.lock b/Library/Homebrew/Gemfile.lock
@@ -18,7 +18,7 @@ GEM
     colorize (0.8.1)
     commander (4.5.2)
       highline (~> 2.0.0)
-    concurrent-ruby (1.1.6)
+    concurrent-ruby (1.1.7)
     connection_pool (2.2.3)
     diff-lcs (1.4.4)
     docile (1.3.2)

diff --git a/Library/Homebrew/vendor/bundle/bundler/setup.rb b/Library/Homebrew/vendor/bundle/bundler/setup.rb
@@ -3,7 +3,7 @@
 ruby_engine = defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'
 ruby_version = RbConfig::CONFIG["ruby_version"]
 path = File.expand_path('..', __FILE__)
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/concurrent-ruby-1.1.6/lib/concurrent-ruby"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/concurrent-ruby-1.1.7/lib/concurrent-ruby"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/i18n-1.8.5/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/minitest-5.14.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/thread_safe-0.3.6/lib"
@@ -21,7 +21,10 @@
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/docile-1.3.2/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/simplecov-html-0.12.2/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/simplecov-0.18.5/lib"
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/codecov-0.2.2/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/codecov-0.2.5/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/coderay-1.1.3/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/highline-2.0.3/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/commander-4.5.2/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/connection_pool-2.2.3/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/diff-lcs-1.4.4/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/extensions/universal-darwin-19/2.6.0/unf_ext-0.0.7.7"
@@ -42,13 +45,17 @@
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/ntlm-http-0.1.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/webrobots-0.1.2/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/mechanize-2.7.6/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/method_source-1.0.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/mustache-1.1.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/parallel-1.19.2/lib"
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/parallel_tests-3.0.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/parallel_tests-3.1.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/parser-2.7.1.4/lib"
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/patchelf-1.1.1/lib"
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/plist-3.5.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rainbow-3.0.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/sorbet-runtime-0.5.5823/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/parlour-4.0.1/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/patchelf-1.2.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/plist-3.5.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/pry-0.13.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/extensions/universal-darwin-19/2.6.0/rdiscount-2.2.0.1"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rdiscount-2.2.0.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/regexp_parser-1.7.1/lib"
@@ -62,10 +69,14 @@
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rspec-its-1.3.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rspec-retry-0.6.2/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rspec-wait-0.0.9/lib"
-$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rubocop-ast-0.2.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rubocop-ast-0.3.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/ruby-progressbar-1.10.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/unicode-display_width-1.7.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rubocop-0.88.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rubocop-performance-1.7.1/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/rubocop-rspec-1.42.0/lib"
 $:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/ruby-macho-2.2.0/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/sorbet-static-0.5.5823-universal-darwin-19/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/sorbet-0.5.5823/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/thor-1.0.1/lib"
+$:.unshift "#{path}/../#{ruby_engine}/#{ruby_version}/gems/tapioca-0.4.1/lib"
diff --git a/.../ruby/2.6.0/gems/concurrent-ruby-1.1.6/lib/concurrent-ruby/concurrent/concurrent_ruby.jar b/.../ruby/2.6.0/gems/concurrent-ruby-1.1.6/lib/concurrent-ruby/concurrent/concurrent_ruby.jar
diff --git a/...or/bundle/ruby/2.6.0/gems/concurrent-ruby-1.1.6/lib/concurrent-ruby/concurrent/version.rb b/...or/bundle/ruby/2.6.0/gems/concurrent-ruby-1.1.6/lib/concurrent-ruby/concurrent/version.rb
diff --git a/....6/lib/concurrent-ruby/concurrent-ruby.rb → ....7/lib/concurrent-ruby/concurrent-ruby.rb b/....6/lib/concurrent-ruby/concurrent-ruby.rb → ....7/lib/concurrent-ruby/concurrent-ruby.rb
diff --git a/...y-1.1.6/lib/concurrent-ruby/concurrent.rb → ...y-1.1.7/lib/concurrent-ruby/concurrent.rb b/...y-1.1.6/lib/concurrent-ruby/concurrent.rb → ...y-1.1.7/lib/concurrent-ruby/concurrent.rb
diff --git a/...6/lib/concurrent-ruby/concurrent/agent.rb → ...7/lib/concurrent-ruby/concurrent/agent.rb b/...6/lib/concurrent-ruby/concurrent/agent.rb → ...7/lib/concurrent-ruby/concurrent/agent.rb
diff --git a/...6/lib/concurrent-ruby/concurrent/array.rb → ...7/lib/concurrent-ruby/concurrent/array.rb b/...6/lib/concurrent-ruby/concurrent/array.rb → ...7/lib/concurrent-ruby/concurrent/array.rb
@@ -16,7 +16,7 @@ module Concurrent
   #     operation therefore when two `+=` operations are executed concurrently updates
   #     may be lost. Use `#concat` instead.
   #
-  #   @see http://ruby-doc.org/core-2.2.0/Array.html Ruby standard library `Array`
+  #   @see http://ruby-doc.org/core/Array.html Ruby standard library `Array`
 
   # @!macro internal_implementation_note
   ArrayImplementation = case

diff --git a/...6/lib/concurrent-ruby/concurrent/async.rb → ...7/lib/concurrent-ruby/concurrent/async.rb b/...6/lib/concurrent-ruby/concurrent/async.rb → ...7/lib/concurrent-ruby/concurrent/async.rb
@@ -58,26 +58,6 @@ module Concurrent
   # end
   # ```
   #
-  # When defining a constructor it is critical that the first line be a call to
-  # `super` with no arguments. The `super` method initializes the background
-  # thread and other asynchronous components.
-  #
-  # ```
-  # class BackgroundLogger
-  #   include Concurrent::Async
-  #
-  #   def initialize(level)
-  #     super()
-  #     @logger = Logger.new(STDOUT)
-  #     @logger.level = level
-  #   end
-  #
-  #   def info(msg)
-  #     @logger.info(msg)
-  #   end
-  # end
-  # ```
-  #
   # Mixing this module into a class provides each object two proxy methods:
   # `async` and `await`. These methods are thread safe with respect to the
   # enclosing object. The former proxy allows methods to be called
@@ -309,6 +289,7 @@ def initialize(delegate)
         @delegate = delegate
         @queue = []
         @executor = Concurrent.global_io_executor
+        @ruby_pid = $$
       end
 
       # Delegates method calls to the wrapped object.
@@ -326,6 +307,7 @@ def method_missing(method, *args, &block)
 
         ivar = Concurrent::IVar.new
         synchronize do
+          reset_if_forked
           @queue.push [ivar, method, args, block]
           @executor.post { perform } if @queue.length == 1
         end
@@ -361,6 +343,13 @@ def perform
           end
         end
       end
+
+      def reset_if_forked
+        if $$ != @ruby_pid
+          @queue.clear
+          @ruby_pid = $$
+        end
+      end
     end
     private_constant :AsyncDelegator
 

diff --git a/....6/lib/concurrent-ruby/concurrent/atom.rb → ....7/lib/concurrent-ruby/concurrent/atom.rb b/....6/lib/concurrent-ruby/concurrent/atom.rb → ....7/lib/concurrent-ruby/concurrent/atom.rb
diff --git a/...rrent/atomic/abstract_thread_local_var.rb → ...rrent/atomic/abstract_thread_local_var.rb b/...rrent/atomic/abstract_thread_local_var.rb → ...rrent/atomic/abstract_thread_local_var.rb
diff --git a/...-ruby/concurrent/atomic/atomic_boolean.rb → ...-ruby/concurrent/atomic/atomic_boolean.rb b/...-ruby/concurrent/atomic/atomic_boolean.rb → ...-ruby/concurrent/atomic/atomic_boolean.rb
diff --git a/...t-ruby/concurrent/atomic/atomic_fixnum.rb → ...t-ruby/concurrent/atomic/atomic_fixnum.rb b/...t-ruby/concurrent/atomic/atomic_fixnum.rb → ...t-ruby/concurrent/atomic/atomic_fixnum.rb
diff --git a/...rrent/atomic/atomic_markable_reference.rb → ...rrent/atomic/atomic_markable_reference.rb b/...rrent/atomic/atomic_markable_reference.rb → ...rrent/atomic/atomic_markable_reference.rb
diff --git a/...uby/concurrent/atomic/atomic_reference.rb → ...uby/concurrent/atomic/atomic_reference.rb b/...uby/concurrent/atomic/atomic_reference.rb → ...uby/concurrent/atomic/atomic_reference.rb
diff --git a/...uby/concurrent/atomic/count_down_latch.rb → ...uby/concurrent/atomic/count_down_latch.rb b/...uby/concurrent/atomic/count_down_latch.rb → ...uby/concurrent/atomic/count_down_latch.rb
diff --git a/...-ruby/concurrent/atomic/cyclic_barrier.rb → ...-ruby/concurrent/atomic/cyclic_barrier.rb b/...-ruby/concurrent/atomic/cyclic_barrier.rb → ...-ruby/concurrent/atomic/cyclic_barrier.rb
diff --git a/...oncurrent-ruby/concurrent/atomic/event.rb → ...oncurrent-ruby/concurrent/atomic/event.rb b/...oncurrent-ruby/concurrent/atomic/event.rb → ...oncurrent-ruby/concurrent/atomic/event.rb
diff --git a/...oncurrent/atomic/java_count_down_latch.rb → ...oncurrent/atomic/java_count_down_latch.rb b/...oncurrent/atomic/java_count_down_latch.rb → ...oncurrent/atomic/java_count_down_latch.rb
diff --git a/...oncurrent/atomic/java_thread_local_var.rb → ...oncurrent/atomic/java_thread_local_var.rb b/...oncurrent/atomic/java_thread_local_var.rb → ...oncurrent/atomic/java_thread_local_var.rb
diff --git a/...concurrent/atomic/mutex_atomic_boolean.rb → ...concurrent/atomic/mutex_atomic_boolean.rb b/...concurrent/atomic/mutex_atomic_boolean.rb → ...concurrent/atomic/mutex_atomic_boolean.rb
diff --git a/.../concurrent/atomic/mutex_atomic_fixnum.rb → .../concurrent/atomic/mutex_atomic_fixnum.rb b/.../concurrent/atomic/mutex_atomic_fixnum.rb → .../concurrent/atomic/mutex_atomic_fixnum.rb
diff --git a/...ncurrent/atomic/mutex_count_down_latch.rb → ...ncurrent/atomic/mutex_count_down_latch.rb b/...ncurrent/atomic/mutex_count_down_latch.rb → ...ncurrent/atomic/mutex_count_down_latch.rb
diff --git a/...ruby/concurrent/atomic/mutex_semaphore.rb → ...ruby/concurrent/atomic/mutex_semaphore.rb b/...ruby/concurrent/atomic/mutex_semaphore.rb → ...ruby/concurrent/atomic/mutex_semaphore.rb
diff --git a/...ruby/concurrent/atomic/read_write_lock.rb → ...ruby/concurrent/atomic/read_write_lock.rb b/...ruby/concurrent/atomic/read_write_lock.rb → ...ruby/concurrent/atomic/read_write_lock.rb
diff --git a/...rrent/atomic/reentrant_read_write_lock.rb → ...rrent/atomic/reentrant_read_write_lock.rb b/...rrent/atomic/reentrant_read_write_lock.rb → ...rrent/atomic/reentrant_read_write_lock.rb
diff --git a/...oncurrent/atomic/ruby_thread_local_var.rb → ...oncurrent/atomic/ruby_thread_local_var.rb b/...oncurrent/atomic/ruby_thread_local_var.rb → ...oncurrent/atomic/ruby_thread_local_var.rb
@@ -28,38 +28,27 @@ class RubyThreadLocalVar < AbstractThreadLocalVar
     # But when a Thread is GC'd, we need to drop the reference to its thread-local
     #   array, so we don't leak memory
 
-    # @!visibility private
-    FREE   = []
-    LOCK   = Mutex.new
-    ARRAYS = {} # used as a hash set
-    # noinspection RubyClassVariableUsageInspection
-    @@next = 0
-    QUEUE  = Queue.new
-    THREAD = Thread.new do
-      while true
-        method, i = QUEUE.pop
-        case method
-        when :thread_local_finalizer
-          LOCK.synchronize do
-            FREE.push(i)
-            # The cost of GC'ing a TLV is linear in the number of threads using TLVs
-            # But that is natural! More threads means more storage is used per TLV
-            # So naturally more CPU time is required to free more storage
-            ARRAYS.each_value do |array|
-              array[i] = nil
-            end
-          end
-        when :thread_finalizer
-          LOCK.synchronize do
-            # The thread which used this thread-local array is now gone
-            # So don't hold onto a reference to the array (thus blocking GC)
-            ARRAYS.delete(i)
-          end
-        end
+    FREE                = []
+    LOCK                = Mutex.new
+    THREAD_LOCAL_ARRAYS = {} # used as a hash set
+
+    # synchronize when not on MRI
+    # on MRI using lock in finalizer leads to "can't be called from trap context" error
+    # so the code is carefully written to be tread-safe on MRI relying on GIL
+
+    if Concurrent.on_cruby?
+      # @!visibility private
+      def self.semi_sync(&block)
+        block.call
+      end
+    else
+      # @!visibility private
+      def self.semi_sync(&block)
+        LOCK.synchronize(&block)
       end
     end
 
-    private_constant :FREE, :LOCK, :ARRAYS, :QUEUE, :THREAD
+    private_constant :FREE, :LOCK, :THREAD_LOCAL_ARRAYS
 
     # @!macro thread_local_var_method_get
     def value
@@ -85,7 +74,7 @@ def value=(value)
       # Using Ruby's built-in thread-local storage is faster
       unless (array = get_threadlocal_array(me))
         array = set_threadlocal_array([], me)
-        LOCK.synchronize { ARRAYS[array.object_id] = array }
+        self.class.semi_sync { THREAD_LOCAL_ARRAYS[array.object_id] = array }
         ObjectSpace.define_finalizer(me, self.class.thread_finalizer(array.object_id))
       end
       array[@index] = (value.nil? ? NULL : value)
@@ -95,32 +84,50 @@ def value=(value)
     protected
 
     # @!visibility private
-    # noinspection RubyClassVariableUsageInspection
     def allocate_storage
-      @index = LOCK.synchronize do
-        FREE.pop || begin
-          result = @@next
-          @@next += 1
-          result
-        end
-      end
+      @index = FREE.pop || next_index
+
       ObjectSpace.define_finalizer(self, self.class.thread_local_finalizer(@index))
     end
 
     # @!visibility private
     def self.thread_local_finalizer(index)
-      # avoid error: can't be called from trap context
-      proc { QUEUE.push [:thread_local_finalizer, index] }
+      proc do
+        semi_sync do
+          # The cost of GC'ing a TLV is linear in the number of threads using TLVs
+          # But that is natural! More threads means more storage is used per TLV
+          # So naturally more CPU time is required to free more storage
+          THREAD_LOCAL_ARRAYS.each_value { |array| array[index] = nil }
+          # free index has to be published after the arrays are cleared
+          FREE.push(index)
+        end
+      end
     end
 
     # @!visibility private
     def self.thread_finalizer(id)
-      # avoid error: can't be called from trap context
-      proc { QUEUE.push [:thread_finalizer, id] }
+      proc do
+        semi_sync do
+          # The thread which used this thread-local array is now gone
+          # So don't hold onto a reference to the array (thus blocking GC)
+          THREAD_LOCAL_ARRAYS.delete(id)
+        end
+      end
     end
 
     private
 
+    # noinspection RubyClassVariableUsageInspection
+    @@next = 0
+    # noinspection RubyClassVariableUsageInspection
+    def next_index
+      LOCK.synchronize do
+        result = @@next
+        @@next += 1
+        result
+      end
+    end
+
     if Thread.instance_methods.include?(:thread_variable_get)
 
       def get_threadlocal_array(thread = Thread.current)

diff --git a/...rrent-ruby/concurrent/atomic/semaphore.rb → ...rrent-ruby/concurrent/atomic/semaphore.rb b/...rrent-ruby/concurrent/atomic/semaphore.rb → ...rrent-ruby/concurrent/atomic/semaphore.rb
diff --git a/...uby/concurrent/atomic/thread_local_var.rb → ...uby/concurrent/atomic/thread_local_var.rb b/...uby/concurrent/atomic/thread_local_var.rb → ...uby/concurrent/atomic/thread_local_var.rb
diff --git a/...ncurrent/atomic_reference/mutex_atomic.rb → ...ncurrent/atomic_reference/mutex_atomic.rb b/...ncurrent/atomic_reference/mutex_atomic.rb → ...ncurrent/atomic_reference/mutex_atomic.rb
diff --git a/...t/atomic_reference/numeric_cas_wrapper.rb → ...t/atomic_reference/numeric_cas_wrapper.rb b/...t/atomic_reference/numeric_cas_wrapper.rb → ...t/atomic_reference/numeric_cas_wrapper.rb
diff --git a/...lib/concurrent-ruby/concurrent/atomics.rb → ...lib/concurrent-ruby/concurrent/atomics.rb b/...lib/concurrent-ruby/concurrent/atomics.rb → ...lib/concurrent-ruby/concurrent/atomics.rb
diff --git a/...collection/copy_on_notify_observer_set.rb → ...collection/copy_on_notify_observer_set.rb b/...collection/copy_on_notify_observer_set.rb → ...collection/copy_on_notify_observer_set.rb
diff --git a/.../collection/copy_on_write_observer_set.rb → .../collection/copy_on_write_observer_set.rb b/.../collection/copy_on_write_observer_set.rb → .../collection/copy_on_write_observer_set.rb
diff --git a/...ion/java_non_concurrent_priority_queue.rb → ...ion/java_non_concurrent_priority_queue.rb b/...ion/java_non_concurrent_priority_queue.rb → ...ion/java_non_concurrent_priority_queue.rb
diff --git a/.../concurrent/collection/lock_free_stack.rb → .../concurrent/collection/lock_free_stack.rb b/.../concurrent/collection/lock_free_stack.rb → .../concurrent/collection/lock_free_stack.rb
diff --git a/...ction/map/atomic_reference_map_backend.rb → ...ction/map/atomic_reference_map_backend.rb b/...ction/map/atomic_reference_map_backend.rb → ...ction/map/atomic_reference_map_backend.rb
diff --git a/...current/collection/map/mri_map_backend.rb → ...current/collection/map/mri_map_backend.rb b/...current/collection/map/mri_map_backend.rb → ...current/collection/map/mri_map_backend.rb
@@ -19,7 +19,7 @@ def []=(key, value)
       end
 
       def compute_if_absent(key)
-        if stored_value = _get(key) # fast non-blocking path for the most likely case
+        if NULL != (stored_value = @backend.fetch(key, NULL)) # fast non-blocking path for the most likely case
           stored_value
         else
           @write_lock.synchronize { super }

diff --git a/...lection/map/non_concurrent_map_backend.rb → ...lection/map/non_concurrent_map_backend.rb b/...lection/map/non_concurrent_map_backend.rb → ...lection/map/non_concurrent_map_backend.rb
diff --git a/...ollection/map/synchronized_map_backend.rb → ...ollection/map/synchronized_map_backend.rb b/...ollection/map/synchronized_map_backend.rb → ...ollection/map/synchronized_map_backend.rb
diff --git a/...llection/non_concurrent_priority_queue.rb → ...llection/non_concurrent_priority_queue.rb b/...llection/non_concurrent_priority_queue.rb → ...llection/non_concurrent_priority_queue.rb
diff --git a/...ion/ruby_non_concurrent_priority_queue.rb → ...ion/ruby_non_concurrent_priority_queue.rb b/...ion/ruby_non_concurrent_priority_queue.rb → ...ion/ruby_non_concurrent_priority_queue.rb
diff --git a/...nt-ruby/concurrent/concern/deprecation.rb → ...nt-ruby/concurrent/concern/deprecation.rb b/...nt-ruby/concurrent/concern/deprecation.rb → ...nt-ruby/concurrent/concern/deprecation.rb
diff --git a/...uby/concurrent/concern/dereferenceable.rb → ...uby/concurrent/concern/dereferenceable.rb b/...uby/concurrent/concern/dereferenceable.rb → ...uby/concurrent/concern/dereferenceable.rb
diff --git a/...urrent-ruby/concurrent/concern/logging.rb → ...urrent-ruby/concurrent/concern/logging.rb b/...urrent-ruby/concurrent/concern/logging.rb → ...urrent-ruby/concurrent/concern/logging.rb
diff --git a/...ent-ruby/concurrent/concern/obligation.rb → ...ent-ruby/concurrent/concern/obligation.rb b/...ent-ruby/concurrent/concern/obligation.rb → ...ent-ruby/concurrent/concern/obligation.rb
diff --git a/...ent-ruby/concurrent/concern/observable.rb → ...ent-ruby/concurrent/concern/observable.rb b/...ent-ruby/concurrent/concern/observable.rb → ...ent-ruby/concurrent/concern/observable.rb
diff --git a/.../ruby/2.6.0/gems/concurrent-ruby-1.1.7/lib/concurrent-ruby/concurrent/concurrent_ruby.jar b/.../ruby/2.6.0/gems/concurrent-ruby-1.1.7/lib/concurrent-ruby/concurrent/concurrent_ruby.jar
diff --git a/...ncurrent-ruby/concurrent/configuration.rb → ...ncurrent-ruby/concurrent/configuration.rb b/...ncurrent-ruby/concurrent/configuration.rb → ...ncurrent-ruby/concurrent/configuration.rb
diff --git a/...b/concurrent-ruby/concurrent/constants.rb → ...b/concurrent-ruby/concurrent/constants.rb b/...b/concurrent-ruby/concurrent/constants.rb → ...b/concurrent-ruby/concurrent/constants.rb
diff --git a/...ib/concurrent-ruby/concurrent/dataflow.rb → ...ib/concurrent-ruby/concurrent/dataflow.rb b/...ib/concurrent-ruby/concurrent/dataflow.rb → ...ib/concurrent-ruby/concurrent/dataflow.rb
diff --git a/...6/lib/concurrent-ruby/concurrent/delay.rb → ...7/lib/concurrent-ruby/concurrent/delay.rb b/...6/lib/concurrent-ruby/concurrent/delay.rb → ...7/lib/concurrent-ruby/concurrent/delay.rb
diff --git a/.../lib/concurrent-ruby/concurrent/errors.rb → .../lib/concurrent-ruby/concurrent/errors.rb b/.../lib/concurrent-ruby/concurrent/errors.rb → .../lib/concurrent-ruby/concurrent/errors.rb
diff --git a/...b/concurrent-ruby/concurrent/exchanger.rb → ...b/concurrent-ruby/concurrent/exchanger.rb b/...b/concurrent-ruby/concurrent/exchanger.rb → ...b/concurrent-ruby/concurrent/exchanger.rb
diff --git a/...ent/executor/abstract_executor_service.rb → ...ent/executor/abstract_executor_service.rb b/...ent/executor/abstract_executor_service.rb → ...ent/executor/abstract_executor_service.rb
diff --git a/...concurrent/executor/cached_thread_pool.rb → ...concurrent/executor/cached_thread_pool.rb b/...concurrent/executor/cached_thread_pool.rb → ...concurrent/executor/cached_thread_pool.rb
diff --git a/...y/concurrent/executor/executor_service.rb → ...y/concurrent/executor/executor_service.rb b/...y/concurrent/executor/executor_service.rb → ...y/concurrent/executor/executor_service.rb
diff --git a/.../concurrent/executor/fixed_thread_pool.rb → .../concurrent/executor/fixed_thread_pool.rb b/.../concurrent/executor/fixed_thread_pool.rb → .../concurrent/executor/fixed_thread_pool.rb
@@ -16,6 +16,9 @@ module Concurrent
   #   Default maximum number of seconds a thread in the pool may remain idle
   #   before being reclaimed.
 
+  # @!macro thread_pool_executor_constant_default_synchronous
+  #   Default value of the :synchronous option.
+
   # @!macro thread_pool_executor_attr_reader_max_length
   #   The maximum number of threads that may be created in the pool.
   #   @return [Integer] The maximum number of threads that may be created in the pool.
@@ -40,6 +43,10 @@ module Concurrent
   #   The number of seconds that a thread may be idle before being reclaimed.
   #   @return [Integer] The number of seconds that a thread may be idle before being reclaimed.
 
+  # @!macro thread_pool_executor_attr_reader_synchronous
+  #   Whether or not a value of 0 for :max_queue option means the queue must perform direct hand-off or rather unbounded queue.
+  #   @return [true, false]
+
   # @!macro thread_pool_executor_attr_reader_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` subsequent tasks will be rejected in

diff --git a/...concurrent/executor/immediate_executor.rb → ...concurrent/executor/immediate_executor.rb b/...concurrent/executor/immediate_executor.rb → ...concurrent/executor/immediate_executor.rb
diff --git a/...t/executor/indirect_immediate_executor.rb → ...t/executor/indirect_immediate_executor.rb b/...t/executor/indirect_immediate_executor.rb → ...t/executor/indirect_immediate_executor.rb
diff --git a/...current/executor/java_executor_service.rb → ...current/executor/java_executor_service.rb b/...current/executor/java_executor_service.rb → ...current/executor/java_executor_service.rb
diff --git a/...t/executor/java_single_thread_executor.rb → ...t/executor/java_single_thread_executor.rb b/...t/executor/java_single_thread_executor.rb → ...t/executor/java_single_thread_executor.rb
diff --git a/...ent/executor/java_thread_pool_executor.rb → ...ent/executor/java_thread_pool_executor.rb b/...ent/executor/java_thread_pool_executor.rb → ...ent/executor/java_thread_pool_executor.rb
@@ -21,12 +21,18 @@ class JavaThreadPoolExecutor < JavaExecutorService
       # @!macro thread_pool_executor_constant_default_thread_timeout
       DEFAULT_THREAD_IDLETIMEOUT = 60
 
+      # @!macro thread_pool_executor_constant_default_synchronous
+      DEFAULT_SYNCHRONOUS = false
+
       # @!macro thread_pool_executor_attr_reader_max_length
       attr_reader :max_length
 
       # @!macro thread_pool_executor_attr_reader_max_queue
       attr_reader :max_queue
 
+      # @!macro thread_pool_executor_attr_reader_synchronous
+      attr_reader :synchronous
+
       # @!macro thread_pool_executor_method_initialize
       def initialize(opts = {})
         super(opts)
@@ -94,16 +100,22 @@ def ns_initialize(opts)
         max_length       = opts.fetch(:max_threads, DEFAULT_MAX_POOL_SIZE).to_i
         idletime         = opts.fetch(:idletime, DEFAULT_THREAD_IDLETIMEOUT).to_i
         @max_queue       = opts.fetch(:max_queue, DEFAULT_MAX_QUEUE_SIZE).to_i
+        @synchronous     = opts.fetch(:synchronous, DEFAULT_SYNCHRONOUS)
         @fallback_policy = opts.fetch(:fallback_policy, :abort)
 
+        raise ArgumentError.new("`synchronous` cannot be set unless `max_queue` is 0") if @synchronous && @max_queue > 0
         raise ArgumentError.new("`max_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if max_length < DEFAULT_MIN_POOL_SIZE
         raise ArgumentError.new("`max_threads` cannot be greater than #{DEFAULT_MAX_POOL_SIZE}") if max_length > DEFAULT_MAX_POOL_SIZE
         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
         raise ArgumentError.new("#{fallback_policy} is not a valid fallback policy") unless FALLBACK_POLICY_CLASSES.include?(@fallback_policy)
 
         if @max_queue == 0
-          queue = java.util.concurrent.LinkedBlockingQueue.new
+          if @synchronous
+            queue = java.util.concurrent.SynchronousQueue.new
+          else
+            queue = java.util.concurrent.LinkedBlockingQueue.new
+          end
         else
           queue = java.util.concurrent.LinkedBlockingQueue.new(@max_queue)
         end

diff --git a/...current/executor/ruby_executor_service.rb → ...current/executor/ruby_executor_service.rb b/...current/executor/ruby_executor_service.rb → ...current/executor/ruby_executor_service.rb
diff --git a/...t/executor/ruby_single_thread_executor.rb → ...t/executor/ruby_single_thread_executor.rb b/...t/executor/ruby_single_thread_executor.rb → ...t/executor/ruby_single_thread_executor.rb
diff --git a/...ent/executor/ruby_thread_pool_executor.rb → ...ent/executor/ruby_thread_pool_executor.rb b/...ent/executor/ruby_thread_pool_executor.rb → ...ent/executor/ruby_thread_pool_executor.rb
@@ -23,6 +23,9 @@ class RubyThreadPoolExecutor < RubyExecutorService
     # @!macro thread_pool_executor_constant_default_thread_timeout
     DEFAULT_THREAD_IDLETIMEOUT = 60
 
+    # @!macro thread_pool_executor_constant_default_synchronous
+    DEFAULT_SYNCHRONOUS = false
+
     # @!macro thread_pool_executor_attr_reader_max_length
     attr_reader :max_length
 
@@ -35,6 +38,9 @@ class RubyThreadPoolExecutor < RubyExecutorService
     # @!macro thread_pool_executor_attr_reader_max_queue
     attr_reader :max_queue
 
+    # @!macro thread_pool_executor_attr_reader_synchronous
+    attr_reader :synchronous
+
     # @!macro thread_pool_executor_method_initialize
     def initialize(opts = {})
       super(opts)
@@ -114,9 +120,11 @@ def ns_initialize(opts)
       @max_length      = opts.fetch(:max_threads, DEFAULT_MAX_POOL_SIZE).to_i
       @idletime        = opts.fetch(:idletime, DEFAULT_THREAD_IDLETIMEOUT).to_i
       @max_queue       = opts.fetch(:max_queue, DEFAULT_MAX_QUEUE_SIZE).to_i
+      @synchronous     = opts.fetch(:synchronous, DEFAULT_SYNCHRONOUS)
       @fallback_policy = opts.fetch(:fallback_policy, :abort)
-      raise ArgumentError.new("#{@fallback_policy} is not a valid fallback policy") unless FALLBACK_POLICIES.include?(@fallback_policy)
 
+      raise ArgumentError.new("`synchronous` cannot be set unless `max_queue` is 0") if @synchronous && @max_queue > 0
+      raise ArgumentError.new("#{@fallback_policy} is not a valid fallback policy") unless FALLBACK_POLICIES.include?(@fallback_policy)
       raise ArgumentError.new("`max_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if @max_length < DEFAULT_MIN_POOL_SIZE
       raise ArgumentError.new("`max_threads` cannot be greater than #{DEFAULT_MAX_POOL_SIZE}") if @max_length > DEFAULT_MAX_POOL_SIZE
       raise ArgumentError.new("`min_threads` cannot be less than #{DEFAULT_MIN_POOL_SIZE}") if @min_length < DEFAULT_MIN_POOL_SIZE
@@ -201,6 +209,8 @@ def ns_assign_worker(*args, &task)
     #
     # @!visibility private
     def ns_enqueue(*args, &task)
+      return false if @synchronous
+
       if !ns_limited_queue? || @queue.size < @max_queue
         @queue << [task, args]
         true

diff --git a/...concurrent/executor/safe_task_executor.rb → ...concurrent/executor/safe_task_executor.rb b/...concurrent/executor/safe_task_executor.rb → ...concurrent/executor/safe_task_executor.rb
diff --git a/...rrent/executor/serial_executor_service.rb → ...rrent/executor/serial_executor_service.rb b/...rrent/executor/serial_executor_service.rb → ...rrent/executor/serial_executor_service.rb
diff --git a/...ncurrent/executor/serialized_execution.rb → ...ncurrent/executor/serialized_execution.rb b/...ncurrent/executor/serialized_execution.rb → ...ncurrent/executor/serialized_execution.rb
diff --git a/...xecutor/serialized_execution_delegator.rb → ...xecutor/serialized_execution_delegator.rb b/...xecutor/serialized_execution_delegator.rb → ...xecutor/serialized_execution_delegator.rb
diff --git a/...rrent/executor/simple_executor_service.rb → ...rrent/executor/simple_executor_service.rb b/...rrent/executor/simple_executor_service.rb → ...rrent/executor/simple_executor_service.rb
diff --git a/...urrent/executor/single_thread_executor.rb → ...urrent/executor/single_thread_executor.rb b/...urrent/executor/single_thread_executor.rb → ...urrent/executor/single_thread_executor.rb
diff --git a/...ncurrent/executor/thread_pool_executor.rb → ...ncurrent/executor/thread_pool_executor.rb b/...ncurrent/executor/thread_pool_executor.rb → ...ncurrent/executor/thread_pool_executor.rb
@@ -73,7 +73,8 @@ class ThreadPoolExecutor < ThreadPoolExecutorImplementation
     #   @option opts [Symbol] :fallback_policy (:abort) the policy for handling new
     #     tasks that are received when the queue size has reached
     #     `max_queue` or the executor has shut down
-    #
+    #   @option opts [Boolean] :synchronous (DEFAULT_SYNCHRONOUS) whether or not a value of 0
+    #     for :max_queue means the queue must perform direct hand-off rather than unbounded.
     #   @raise [ArgumentError] if `:max_threads` is less than one
     #   @raise [ArgumentError] if `:min_threads` is less than zero
     #   @raise [ArgumentError] if `:fallback_policy` is not one of the values specified

diff --git a/...ent-ruby/concurrent/executor/timer_set.rb → ...ent-ruby/concurrent/executor/timer_set.rb b/...ent-ruby/concurrent/executor/timer_set.rb → ...ent-ruby/concurrent/executor/timer_set.rb
diff --git a/...b/concurrent-ruby/concurrent/executors.rb → ...b/concurrent-ruby/concurrent/executors.rb b/...b/concurrent-ruby/concurrent/executors.rb → ...b/concurrent-ruby/concurrent/executors.rb
diff --git a/.../lib/concurrent-ruby/concurrent/future.rb → .../lib/concurrent-ruby/concurrent/future.rb b/.../lib/concurrent-ruby/concurrent/future.rb → .../lib/concurrent-ruby/concurrent/future.rb
diff --git a/....6/lib/concurrent-ruby/concurrent/hash.rb → ....7/lib/concurrent-ruby/concurrent/hash.rb b/....6/lib/concurrent-ruby/concurrent/hash.rb → ....7/lib/concurrent-ruby/concurrent/hash.rb
@@ -10,7 +10,7 @@ module Concurrent
   #   or writing at a time. This includes iteration methods like `#each`,
   #   which takes the lock repeatedly when reading an item.
   #
-  #   @see http://ruby-doc.org/core-2.2.0/Hash.html Ruby standard library `Hash`
+  #   @see http://ruby-doc.org/core/Hash.html Ruby standard library `Hash`
 
   # @!macro internal_implementation_note
   HashImplementation = case