Posible bug: spin_some only processes one message per topic even if m…

…ultiple messages are in the queue

  ros2/rclcpp#2655

Signed-off-by: Tomoya Fujita <[email protected]>

prover_rclcpp/CMakeLists.txt

@@ -159,6 +159,7 @@ custom_executable(rclcpp_2497)
 custom_executable(rclcpp_2507)
 custom_executable(rclcpp_2645)
 #custom_executable(rclcpp_2654)
+custom_executable(rclcpp_2655)
 custom_executable(rclcpp_2664)
 
 custom_executable(rosbag2_1586)

prover_rclcpp/src/rclcpp_2655.cpp

@@ -0,0 +1,42 @@
+#include <rclcpp/node.hpp>
+#include <rclcpp/executors.hpp>
+#include <std_msgs/msg/string.hpp>
+
+int main(int argc, char *argv[]) {
+  rclcpp::init(argc, argv);
+
+  rclcpp::Node::SharedPtr pub_node = std::make_shared<rclcpp::Node>("publisher");
+  auto pub = pub_node->create_publisher<std_msgs::msg::String>("topic", 100);
+  int count = 0;
+  auto timer_pub = pub_node->create_wall_timer(std::chrono::milliseconds(100), [&]() -> void {
+    std_msgs::msg::String msg;
+    msg.data = std::to_string(count);
+    count++;
+    pub->publish(msg);
+    std::cout << "Published: " << msg.data << std::endl;
+  });
+  std::thread pub_node_thread([&]() {
+    rclcpp::spin(pub_node);
+  });
+
+  rclcpp::Node::SharedPtr sub_node = std::make_shared<rclcpp::Node>("subscriber");
+  auto sub1 =
+      sub_node->create_subscription<std_msgs::msg::String>("topic", 100, [](std_msgs::msg::String::ConstSharedPtr msg) {
+        std::cout << "Received(sub1): " << msg->data << std::endl;
+      });
+  auto sub2 =
+      sub_node->create_subscription<std_msgs::msg::String>("topic", 100, [](std_msgs::msg::String::ConstSharedPtr msg) {
+        std::cout << "Received(sub2): " << msg->data << std::endl;
+      });
+
+  while (rclcpp::ok()) {
+    std::cout << "Running spin_some" << std::endl;
+    rclcpp::spin_some(sub_node);
+    std::this_thread::sleep_for(std::chrono::seconds(1));
+  }
+
+  pub_node_thread.join();
+  rclcpp::shutdown();
+
+  return 0;
+}