fix(system_monitor): move top command execution to a timer

system/system_monitor/include/system_monitor/process_monitor/process_monitor.hpp

@@ -27,6 +27,7 @@
 #include <boost/process.hpp>
 
 #include <memory>
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -41,11 +42,6 @@ class ProcessMonitor : public rclcpp::Node
    */
   explicit ProcessMonitor(const rclcpp::NodeOptions & options);
 
-  /**
-   * @brief Update the diagnostic state
-   */
-  void update();
-
 protected:
   using DiagStatus = diagnostic_msgs::msg::DiagnosticStatus;
 
@@ -110,6 +106,11 @@ class ProcessMonitor : public rclcpp::Node
     std::vector<std::shared_ptr<DiagTask>> * tasks, const std::string & message,
     const std::string & error_command, const std::string & content);
 
+  /**
+   * @brief timer callback to execute top command
+   */
+  void onTimer();
+
   diagnostic_updater::Updater updater_;  //!< @brief Updater class which advertises to /diagnostics
 
   char hostname_[HOST_NAME_MAX + 1];  //!< @brief host name
@@ -118,7 +119,13 @@ class ProcessMonitor : public rclcpp::Node
   std::vector<std::shared_ptr<DiagTask>>
     load_tasks_;  //!< @brief list of diagnostics tasks for high load procs
   std::vector<std::shared_ptr<DiagTask>>
-    memory_tasks_;  //!< @brief list of diagnostics tasks for high memory procs
+    memory_tasks_;                      //!< @brief list of diagnostics tasks for high memory procs
+  rclcpp::TimerBase::SharedPtr timer_;  //!< @brief timer to execute top command
+  std::string top_output_;              //!< @brief output from top command
+  bool is_top_error_;                   //!< @brief flag if an error occurs
+  double elapsed_ms_;                   //!< @brief Execution time of top command
+  std::mutex mutex_;                    //!< @brief mutex for output from top command
+  rclcpp::CallbackGroup::SharedPtr timer_callback_group_;  //!< @brief Callback Group
 };
 
 #endif  // SYSTEM_MONITOR__PROCESS_MONITOR__PROCESS_MONITOR_HPP_

system/system_monitor/package.xml

@@ -18,6 +18,7 @@
   <depend>rclcpp</depend>
   <depend>rclcpp_components</depend>
   <depend>std_msgs</depend>
+  <depend>tier4_autoware_utils</depend>
   <depend>tier4_external_api_msgs</depend>
 
   <exec_depend>chrony</exec_depend>

system/system_monitor/src/process_monitor/process_monitor.cpp

@@ -21,6 +21,8 @@
 
 #include "system_monitor/system_monitor_utility.hpp"
 
+#include <tier4_autoware_utils/system/stop_watch.hpp>
+
 #include <fmt/format.h>
 
 #include <memory>
@@ -31,8 +33,11 @@
 ProcessMonitor::ProcessMonitor(const rclcpp::NodeOptions & options)
 : Node("process_monitor", options),
   updater_(this),
-  num_of_procs_(declare_parameter<int>("num_of_procs", 5))
+  num_of_procs_(declare_parameter<int>("num_of_procs", 5)),
+  is_top_error_(false)
 {
+  using namespace std::literals::chrono_literals;
+
   int index;
 
   gethostname(hostname_, sizeof(hostname_));
@@ -50,33 +55,40 @@ ProcessMonitor::ProcessMonitor(const rclcpp::NodeOptions & options)
     memory_tasks_.push_back(task);
     updater_.add(*task);
   }
-}
 
-void ProcessMonitor::update() { updater_.force_update(); }
+  // Start timer to execute top command
+  timer_callback_group_ = this->create_callback_group(rclcpp::CallbackGroupType::MutuallyExclusive);
+  timer_ = rclcpp::create_timer(
+    this, get_clock(), 1s, std::bind(&ProcessMonitor::onTimer, this), timer_callback_group_);
+}
 
 void ProcessMonitor::monitorProcesses(diagnostic_updater::DiagnosticStatusWrapper & stat)
 {
-  // Remember start time to measure elapsed time
-  const auto t_start = SystemMonitorUtility::startMeasurement();
-
-  bp::ipstream is_err;
-  bp::ipstream is_out;
-  std::ostringstream os;
+  // thread-safe read
+  std::string str;
+  bool is_top_error;
+  double elapsed_ms;
+  {
+    std::lock_guard<std::mutex> lock(mutex_);
+    str = top_output_;
+    is_top_error = is_top_error_;
+    elapsed_ms = elapsed_ms_;
+  }
 
-  // Get processes
-  bp::child c("top -bn1 -o %CPU -w 128", bp::std_out > is_out, bp::std_err > is_err);
-  c.wait();
-  if (c.exit_code() != 0) {
-    is_err >> os.rdbuf();
+  if (is_top_error) {
     stat.summary(DiagStatus::ERROR, "top error");
-    stat.add("top", os.str().c_str());
-    setErrorContent(&load_tasks_, "top error", "top", os.str().c_str());
-    setErrorContent(&memory_tasks_, "top error", "top", os.str().c_str());
+    stat.add("top", str);
+    setErrorContent(&load_tasks_, "top error", "top", str);
+    setErrorContent(&memory_tasks_, "top error", "top", str);
     return;
   }
 
-  is_out >> os.rdbuf();
-  std::string str = os.str();
+  // If top still not running
+  if (str.empty()) {
+    // Send OK tentatively
+    stat.summary(DiagStatus::OK, "starting up");
+    return;
+  }
 
   // Get task summary
   getTasksSummary(stat, str);
@@ -89,8 +101,7 @@ void ProcessMonitor::monitorProcesses(diagnostic_updater::DiagnosticStatusWrappe
   // Get high memory processes
   getHighMemoryProcesses(str);
 
-  // Measure elapsed time since start time and report
-  SystemMonitorUtility::stopMeasurement(t_start, stat);
+  stat.addf("execution time", "%f ms", elapsed_ms);
 }
 
 void ProcessMonitor::getTasksSummary(
@@ -310,5 +321,39 @@ void ProcessMonitor::setErrorContent(
   }
 }
 
+void ProcessMonitor::onTimer()
+{
+  bool is_top_error = false;
+
+  // Start to measure elapsed time
+  tier4_autoware_utils::StopWatch<std::chrono::milliseconds> stop_watch;
+  stop_watch.tic("execution_time");
+
+  bp::ipstream is_err;
+  bp::ipstream is_out;
+  std::ostringstream os;
+
+  // Get processes
+  bp::child c("top -bn1 -o %CPU -w 128", bp::std_out > is_out, bp::std_err > is_err);
+  c.wait();
+
+  if (c.exit_code() != 0) {
+    is_top_error = true;
+    is_err >> os.rdbuf();
+  } else {
+    is_out >> os.rdbuf();
+  }
+
+  const double elapsed_ms = stop_watch.toc("execution_time");
+
+  // thread-safe copy
+  {
+    std::lock_guard<std::mutex> lock(mutex_);
+    top_output_ = os.str();
+    is_top_error_ = is_top_error;
+    elapsed_ms_ = elapsed_ms;
+  }
+}
+
 #include <rclcpp_components/register_node_macro.hpp>
 RCLCPP_COMPONENTS_REGISTER_NODE(ProcessMonitor)