Cleaner shutdown.

arangodb · neunhoef · Jul 11, 2025 · Jun 27, 2025 · Jun 27, 2025 · Jun 27, 2025
commit b5950e672435fa8965d1c3e9a6c161da06acaa95
diff --git a/arangod/RestServer/arangod.cpp b/arangod/RestServer/arangod.cpp
@@ -58,7 +58,9 @@ constexpr auto kNonServerFeatures =
 
 static int runServer(int argc, char** argv, ArangoGlobalContext& context) {
   try {
-    CrashHandler::installCrashHandler();
+    CrashHandler crashHandler;  // initializes the crash handler and starts its
+                                // thread the destructor will stop it.
+
     std::string name = context.binaryName();
 
     auto options = std::make_shared<arangodb::options::ProgramOptions>(
@@ -181,9 +183,9 @@ static int runServer(int argc, char** argv, ArangoGlobalContext& context) {
           return std::make_unique<ShutdownFeature>(
               server,
 #ifdef USE_V8
-              std::array { ArangodServer::id<ScriptFeature>() }
+              std::array{ArangodServer::id<ScriptFeature>()}
 #else
-              std::array { ArangodServer::id<AgencyFeaturePhase>() }
+              std::array{ArangodServer::id<AgencyFeaturePhase>()}
 #endif
           );
         },
@@ -227,10 +229,8 @@ static int runServer(int argc, char** argv, ArangoGlobalContext& context) {
       ret = EXIT_FAILURE;
     }
 
-    // Shutdown the crash handler thread in a controlled manner
-    CrashHandler::shutdownCrashHandler();
-
     Logger::flush();
+    // CrashHandler will be deactivated here automatically be its destructor
     return context.exit(ret);
   } catch (std::exception const& ex) {
     LOG_TOPIC("8afa8", ERR, arangodb::Logger::FIXME)

diff --git a/lib/ApplicationFeatures/VersionFeature.cpp b/lib/ApplicationFeatures/VersionFeature.cpp
@@ -64,7 +64,7 @@ void VersionFeature::validateOptions(std::shared_ptr<ProgramOptions>) {
     }
 
     std::cout << builder.slice().toJson() << std::endl;
-    CrashHandler::shutdownCrashHandler();
+    // CrashHandler::shutdownCrashHandler();
     exit(EXIT_SUCCESS);
   }
 
@@ -74,7 +74,7 @@ void VersionFeature::validateOptions(std::shared_ptr<ProgramOptions>) {
               << LGPLNotice << std::endl
               << std::endl
               << Version::getDetailed() << std::endl;
-    CrashHandler::shutdownCrashHandler();
+    // CrashHandler::shutdownCrashHandler();
     exit(EXIT_SUCCESS);
   }
 }

diff --git a/lib/CrashHandler/CrashHandler.cpp b/lib/CrashHandler/CrashHandler.cpp
@@ -503,6 +503,8 @@ void crashHandlerSignalHandler(int signal, siginfo_t* info, void* ucontext) {
 
 namespace arangodb {
 
+std::atomic<CrashHandler*> CrashHandler::_theCrashHandler;
+
 void CrashHandler::triggerCrashHandler() {
   ::crashHandlerState.store(arangodb::CrashHandlerState::CRASH_DETECTED,
                             std::memory_order_release);
@@ -685,6 +687,13 @@ void CrashHandler::installCrashHandler() {
 
     CrashHandler::crash(buffer.view());
   });
+
+  std::atexit([]() {
+    CrashHandler* ch = CrashHandler::_theCrashHandler;
-    CrashHandler* ch = CrashHandler::_theCrashHandler;
+    auto* ch = CrashHandler::_theCrashHandler.exchange(nullptr);
-    CrashHandler* ch = CrashHandler::_theCrashHandler;
+    auto* ch = CrashHandler::_theCrashHandler.exchange(nullptr);
+    if (ch != nullptr) {
+      ch->shutdownCrashHandler();
+    }
+  });
 }
 
 /// @brief shuts down the crash handler thread

diff --git a/lib/CrashHandler/CrashHandler.h b/lib/CrashHandler/CrashHandler.h
@@ -23,11 +23,12 @@
 
 #pragma once
 
+#include <atomic>
 #include <string_view>
 
 namespace arangodb {
 
-/// @brief States for the crash handler thread coordination
+/// @brief States for the crash handler thread coordination.
 /// The state of the dedicated crash handler starts with IDLE
 /// and moves to CRASH_DETECTED when a crash is detected. When the
 /// thread has handled the situation it goes to HANDLING_COMPLETE
@@ -42,7 +43,29 @@ enum class CrashHandlerState : int {
 };
 
 class CrashHandler {
+  std::atomic<bool> _threadRunning{false};
+  static std::atomic<CrashHandler*> _theCrashHandler;
+  // This needs to be static for the signal handlers to reach!
+
  public:
+  CrashHandler() {
+    // starts global background thread if not already done
+    bool threadRunning = _threadRunning.exchange(true);
+    if (!threadRunning) {
+      _theCrashHandler.store(this);
+      installCrashHandler();
+    }
+  }
+
+  ~CrashHandler() {
+    // joins global background thread if running
+    bool threadRunning = _threadRunning.exchange(false);
+    if (threadRunning) {
+      shutdownCrashHandler();
+    }
+    _theCrashHandler.store(nullptr);
+  }
+
   /// @brief log backtrace for current thread to logfile
   static void logBacktrace();
 
@@ -67,18 +90,19 @@ class CrashHandler {
   /// @brief disable printing of backtraces
   static void disableBacktraces();
 
-  /// @brief installs the crash handler globally
-  static void installCrashHandler();
-
-  /// @brief shuts down the crash handler thread
-  static void shutdownCrashHandler();
-
   /// @brief triggers the crash handler thread to handle a crash
   /// @return true if successfully triggered, false if already in progress
   static void triggerCrashHandler();
 
   /// @brief waits for the crash handler thread to complete its work
   static void waitForCrashHandlerCompletion();
+
+ private:
+  /// @brief installs the crash handler globally
+  static void installCrashHandler();
+
+  /// @brief shuts down the crash handler thread
+  static void shutdownCrashHandler();
 };
 
 }  // namespace arangodb