On Windows, ensure the count of outstanding work is decremented for

abandoned operations (i.e. operations that are being cleaned up within
the io_service destructor).

asio/include/asio/detail/impl/dev_poll_reactor.ipp

@@ -63,6 +63,8 @@ void dev_poll_reactor::shutdown_service()
     op_queue_[i].get_all_operations(ops);
 
   timer_queues_.get_all_timers(ops);
+
+  io_service_.abandon_operations(ops);
 } 
 
 // Helper class to re-register all descriptors with /dev/poll.

asio/include/asio/detail/impl/epoll_reactor.ipp

@@ -84,6 +84,8 @@ void epoll_reactor::shutdown_service()
   }
 
   timer_queues_.get_all_timers(ops);
+
+  io_service_.abandon_operations(ops);
 }
 
 void epoll_reactor::fork_service(asio::io_service::fork_event fork_ev)

asio/include/asio/detail/impl/kqueue_reactor.ipp

@@ -74,6 +74,8 @@ void kqueue_reactor::shutdown_service()
   }
 
   timer_queues_.get_all_timers(ops);
+
+  io_service_.abandon_operations(ops);
 }
 
 void kqueue_reactor::fork_service(asio::io_service::fork_event fork_ev)

asio/include/asio/detail/impl/select_reactor.ipp

@@ -81,6 +81,8 @@ void select_reactor::shutdown_service()
     op_queue_[i].get_all_operations(ops);
 
   timer_queues_.get_all_timers(ops);
+
+  io_service_.abandon_operations(ops);
 }
 
 void select_reactor::fork_service(asio::io_service::fork_event fork_ev)

asio/include/asio/detail/impl/signal_set_service.ipp

@@ -145,6 +145,8 @@ void signal_set_service::shutdown_service()
       reg = reg->next_in_table_;
     }
   }
+
+  io_service_.abandon_operations(ops);
 }
 
 void signal_set_service::fork_service(

asio/include/asio/detail/impl/task_io_service.ipp

@@ -230,6 +230,13 @@ void task_io_service::post_deferred_completions(
   }
 }
 
+void task_io_service::abandon_operations(
+    op_queue<task_io_service::operation>& ops)
+{
+  op_queue<task_io_service::operation> ops2;
+  ops2.push(ops);
+}
+
 std::size_t task_io_service::do_one(mutex::scoped_lock& lock,
     task_io_service::idle_thread_info* this_idle_thread)
 {

asio/include/asio/detail/impl/win_iocp_io_service.ipp

@@ -262,6 +262,17 @@ void win_iocp_io_service::post_deferred_completions(
   }
 }
 
+void win_iocp_io_service::abandon_operations(
+    op_queue<win_iocp_operation>& ops)
+{
+  while (win_iocp_operation* op = ops.front())
+  {
+    ops.pop();
+    ::InterlockedDecrement(&outstanding_work_);
+    op->destroy();
+  }
+}
+
 void win_iocp_io_service::on_pending(win_iocp_operation* op)
 {
   if (::InterlockedCompareExchange(&op->ready_, 1, 0) == 1)

asio/include/asio/detail/task_io_service.hpp

@@ -105,6 +105,10 @@ public:
   // that work_started() was previously called for each operation.
   ASIO_DECL void post_deferred_completions(op_queue<operation>& ops);
 
+  // Process unfinished operations as part of a shutdown_service operation.
+  // Assumes that work_started() was previously called for the operations.
+  ASIO_DECL void abandon_operations(op_queue<operation>& ops);
+
 private:
   // Structure containing information about an idle thread.
   struct idle_thread_info;

asio/include/asio/detail/win_iocp_io_service.hpp

@@ -126,6 +126,10 @@ public:
   ASIO_DECL void post_deferred_completions(
       op_queue<win_iocp_operation>& ops);
 
+  // Enqueue unfinished operation as part of a shutdown_service operation.
+  // Assumes that work_started() was previously called for the operations.
+  ASIO_DECL void abandon_operations(op_queue<operation>& ops);
+
   // Called after starting an overlapped I/O operation that did not complete
   // immediately. The caller must have already called work_started() prior to
   // starting the operation.