[AMQ-7452] Fix "Timer already cancelled" on new connections when shared inactivity timer dies

activemq-client/src/main/java/org/apache/activemq/thread/SchedulerTimerTask.java

@@ -29,19 +29,28 @@ public class SchedulerTimerTask extends TimerTask {
     private static final Logger LOGGER = LoggerFactory.getLogger(SchedulerTimerTask.class);
 
     private final Runnable task;
+    private final boolean terminateOnError;
 
     public SchedulerTimerTask(Runnable task) {
+        this(task, true);
+    }
+
+    public SchedulerTimerTask(Runnable task, boolean terminateOnError) {
         this.task = task;
+        this.terminateOnError = terminateOnError;
     }
 
     public void run() {
         try {
             this.task.run();
         } catch (Error error) {
-            // Very bad error. Can't swallow this but can log it.
             LOGGER.error("Scheduled task error", error);
+            if (terminateOnError) {
+                LOGGER.error("Exiting JVM due to error: {}", error.getMessage());
+                System.exit(1);
+            }
             throw error;
-        } catch (Exception exception) {
+        } catch (Throwable exception) {
             // It is a known issue of java.util.Timer that if a TimerTask.run() method throws an exception, the
             // Timer's thread exits as if Timer.cancel() had been called. This makes the Timer completely unusable from
             // that point on - whenever the Timer triggers there is an 'IllegalStateException: Timer already cancelled'

activemq-client/src/main/java/org/apache/activemq/transport/AbstractInactivityMonitor.java

@@ -417,7 +417,7 @@ public synchronized void startConnectCheckTask(long connectionTimeout) {
             connectCheckerTask = new SchedulerTimerTask(connectChecker);
 
             synchronized (AbstractInactivityMonitor.class) {
-                if (CHECKER_COUNTER == 0) {
+                if (CHECKER_COUNTER == 0 || READ_CHECK_TIMER == null) {
                     if (ASYNC_TASKS == null || ASYNC_TASKS.isShutdown()) {
                         ASYNC_TASKS = createExecutor();
                     }