thread_pool.rb - add backlog_max

lib/puma/thread_pool.rb

@@ -37,6 +37,7 @@ def initialize(name, options = {}, &block)
       @mutex = Mutex.new
 
       @todo = []
+      @backlog_max = 0
 
       @spawned = 0
       @waiting = 0
@@ -91,6 +92,12 @@ def backlog
       with_mutex { @todo.size }
     end
 
+    # The maximum size of the backlog
+    #
+    def backlog_max
+      with_mutex { @backlog_max }
+    end
+
     # @!attribute [r] pool_capacity
     def pool_capacity
       waiting + (@max - spawned)
@@ -227,6 +234,8 @@ def <<(work)
         end
 
         @todo << work
+        t = @todo.size
+        @backlog_max = t if t > @backlog_max
 
         if @waiting < @todo.size and @spawned < @max
           spawn_thread