rclcpp_lifecycle::LifecycleNode::get_current_state is not thread safe #1746
Description
Bug report
Required Info:
- Operating System:
- Ubuntu 20.4
- Installation type:
- binaries
- Version or commit hash:
- foxy
- DDS implementation:
- fastDDS
- Client library (if applicable):
- rclcpp
Steps to reproduce issue
In code below get_current_state is called in 2 threads and after random number of iterations Error in state! Internal state_handle is NULL. is thrown when calling id() state.
The problem disappears if only one thread calls get_current_state function.
#include <chrono>
#include <iostream>
#include <memory>
#include <thread>
#include "lifecycle_msgs/msg/transition.hpp"
#include "rclcpp/rclcpp.hpp"
#include "rclcpp/publisher.hpp"
#include "rclcpp_lifecycle/lifecycle_node.hpp"
#include "rcutils/logging_macros.h"
/// Get current node state in a loop
void checkState(std::shared_ptr<rclcpp_lifecycle::LifecycleNode> node) {
// infinite loop
while (1) {
// This call fails
node->get_current_state().id();
}
}
int main(int argc, char * argv[])
{
setvbuf(stdout, NULL, _IONBF, BUFSIZ);
rclcpp::init(argc, argv);
std::shared_ptr<rclcpp_lifecycle::LifecycleNode> lc_node =
std::make_shared<rclcpp_lifecycle::LifecycleNode>("lc_talker");
lc_node->trigger_transition(lifecycle_msgs::msg::Transition::TRANSITION_CONFIGURE);
// Created multiple threads
std::thread thread_object_1(checkState, lc_node);
std::thread thread_object_2(checkState, lc_node);
// wait
thread_object_1.join();
rclcpp::shutdown();
return 0;
}