Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • from source
• Version or commit hash:
  • dc7e95a
• DDS implementation:
  • N/A
• Client library (if applicable):
  • rclcpp

Steps to reproduce issue

Build the following node:

#include <iostream>
#include <memory>

#include "rclcpp/rclcpp.hpp"

int main(int argc, char ** argv)
{
  rclcpp::init(argc, argv);
  auto node = std::make_shared<rclcpp::Node>("foo_node");

  auto param_change_callback =
    [](std::vector<rclcpp::Parameter> parameters)
    {
      std::cerr << "Parameter callback" << std::endl;
      auto result = rcl_interfaces::msg::SetParametersResult();
      result.successful = true;
      return result;
    };
  auto param_callback_handle = node->add_on_set_parameters_callback(param_change_callback);

  rclcpp::spin(node);

  rclcpp::shutdown();
  return 0;
}

Run it and then set the use_sim_time parameter on it:

ros2 param set /foo_node use_sim_time true

Expected behavior

The parameter is set successfully and the registered callback is called once.

Actual behavior

The parameter is set successfully and the registered callback is called five times.

Additional information

I've experimented with a user-defined parameter, and do not experience this issue (i.e. the parameter callback is called exactly once).