refactored refill of Docker container pool

lib/docker_container_pool.rb

@@ -7,10 +7,8 @@ class DockerContainerPool
 
   def self.clean_up
     @refill_task.try(:shutdown)
-    @containers.each do |key, value|
-      while !value.empty? do
-        DockerClient.destroy_container(value.shift)
-      end
+    @containers.values.each do |containers|
+      DockerClient.destroy_container(containers.shift) until containers.empty?
     end
   end
 
@@ -35,18 +33,22 @@ class DockerContainerPool
   end
 
   def self.refill
-    ExecutionEnvironment.all.each do |execution_environment|
-      refill_count = [execution_environment.pool_size - @containers[execution_environment.id].length, config[:maximum_refill_count]].min
-      if refill_count > 0
-        Concurrent::Future.execute do
-          @containers[execution_environment.id] += refill_count.times.map { create_container(execution_environment) }
-        end
+    ExecutionEnvironment.where('pool_size > 0').each do |execution_environment|
+      if config[:refill][:async]
+        Concurrent::Future.execute { refill_for_execution_environment(execution_environment) }
+      else
+        refill_for_execution_environment(execution_environment)
       end
     end
   end
 
+  def self.refill_for_execution_environment(execution_environment)
+    refill_count = [execution_environment.pool_size - @containers[execution_environment.id].length, config[:refill][:batch_size]].min
+    @containers[execution_environment.id] += refill_count.times.map { create_container(execution_environment) }
+  end
+
   def self.start_refill_task
-    @refill_task = Concurrent::TimerTask.new(execution_interval: config[:interval], run_now: true) { refill }
+    @refill_task = Concurrent::TimerTask.new(execution_interval: config[:refill][:interval], run_now: true, timeout_interval: config[:refill][:timeout]) { refill }
     @refill_task.execute
   end
 end