Reduced pure Ruby max threads below 14751

Author: jdantonio

lib/concurrent/async.rb

@@ -297,7 +297,7 @@ def init_mutex
     #
     # @!visibility private
     def init_synchronization
-      raise InitializationError.new('#init_synchronization was already called') if @__async_initialized__
+      return self if @__async_initialized__
 
       @__async_initialized__ = true
       serializer = Concurrent::SerializedExecution.new

lib/concurrent/executor/ruby_thread_pool_executor.rb

@@ -11,7 +11,7 @@ module Concurrent
   class RubyThreadPoolExecutor < RubyExecutorService
 
     # Default maximum number of threads that will be created in the pool.
-    DEFAULT_MAX_POOL_SIZE      = 2**15 # 32768
+    DEFAULT_MAX_POOL_SIZE      = 2**13 # 8192
 
     # Default minimum number of threads that will be retained in the pool.
     DEFAULT_MIN_POOL_SIZE      = 0