Merge pull request #59 from mauropasse/mauro/fix-deadlock

Unlock queue mutex after taking event

Author: iRobot ROS

rclcpp/include/rclcpp/experimental/buffers/events_queue.hpp

@@ -115,7 +115,7 @@ class EventsQueue
    * @brief gets a single entity event from the queue
    * @return a single entity event
   */
-  // TODO: find an alternative to pop_all_events and
+  // TODO(mauropasse): find an alternative to pop_all_events and
   // get_single_event to use standard queue interfaces
   RCLCPP_PUBLIC
   virtual

rclcpp/src/rclcpp/executors/events_executor.cpp

@@ -141,6 +141,9 @@ EventsExecutor::spin_some_impl(std::chrono::nanoseconds max_duration, bool exhau
       if (has_event) {
         ExecutorEvent event = events_queue_->front();
         events_queue_->pop();
+        // Unlock the mutex, so if the execution of the event requires
+        // pushing an event into the queue we avoid a deadlock.
+        lock.unlock();
         this->execute_event(event);
         executed_events++;
         continue;