ARTEMIS-1447 Reuse thread pools on JDBC Locks

I had moved the initialization of the thread pools for that..
I also have changed the CrticialAnalyzer to use the same pools as part of this

artemis-commons/src/main/java/org/apache/activemq/artemis/core/server/ActiveMQScheduledComponent.java

@@ -188,6 +188,13 @@ public abstract class ActiveMQScheduledComponent implements ActiveMQComponent, R
       return this;
    }
 
+   public synchronized ActiveMQScheduledComponent setPeriod(long period, TimeUnit unit) {
+      this.period = period;
+      this.timeUnit = unit;
+      restartIfNeeded();
+      return this;
+   }
+
    public long getInitialDelay() {
       return initialDelay;
    }

artemis-commons/src/main/java/org/apache/activemq/artemis/utils/critical/CriticalAnalyzerImpl.java

@@ -19,9 +19,10 @@ package org.apache.activemq.artemis.utils.critical;
 
 import java.util.ConcurrentModificationException;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 
+import org.apache.activemq.artemis.core.server.ActiveMQScheduledComponent;
 import org.apache.activemq.artemis.utils.collections.ConcurrentHashSet;
 import org.jboss.logging.Logger;
 
@@ -31,7 +32,29 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
 
    private volatile long timeoutNanoSeconds;
 
-   private volatile long checkTimeNanoSeconds;
+   // one minute by default.. the server will change it for sure
+   private volatile long checkTimeNanoSeconds = TimeUnit.SECONDS.toNanos(60);
+
+   private final ActiveMQScheduledComponent scheduledComponent;
+
+   private final AtomicBoolean running = new AtomicBoolean(false);
+
+   public CriticalAnalyzerImpl() {
+      // this will make the scheduled component to start its own pool
+
+      /* Important: The scheduled component should have its own thread pool...
+       *  otherwise in case of a deadlock, or a starvation of the server the analyzer won't pick up any
+       *  issues and won't be able to shutdown the server or halt the VM
+       */
+      this.scheduledComponent = new ActiveMQScheduledComponent(null, null, checkTimeNanoSeconds, TimeUnit.NANOSECONDS, false) {
+         @Override
+         public void run() {
+            logger.trace("Checking critical analyzer");
+            check();
+         }
+      };
+
+   }
 
    @Override
    public void clear() {
@@ -41,10 +64,6 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
 
    private CopyOnWriteArrayList<CriticalAction> actions = new CopyOnWriteArrayList<>();
 
-   private Thread thread;
-
-   private final Semaphore running = new Semaphore(1);
-
    private final ConcurrentHashSet<CriticalComponent> components = new ConcurrentHashSet<>();
 
    @Override
@@ -65,6 +84,7 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
    @Override
    public CriticalAnalyzer setCheckTime(long timeout, TimeUnit unit) {
       this.checkTimeNanoSeconds = unit.toNanos(timeout);
+      this.scheduledComponent.setPeriod(timeout, unit);
       return this;
    }
 
@@ -78,6 +98,9 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
 
    @Override
    public CriticalAnalyzer setTimeout(long timeout, TimeUnit unit) {
+      if (checkTimeNanoSeconds <= 0) {
+         this.setCheckTime(timeout / 2, unit);
+      }
       this.timeoutNanoSeconds = unit.toNanos(timeout);
       return this;
    }
@@ -117,7 +140,7 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
    }
 
    private void fireAction(CriticalComponent component) {
-      for (CriticalAction action: actions) {
+      for (CriticalAction action : actions) {
          try {
             action.run(component);
          } catch (Throwable e) {
@@ -128,59 +151,17 @@ public class CriticalAnalyzerImpl implements CriticalAnalyzer {
 
    @Override
    public void start() {
+      scheduledComponent.start();
 
-      if (!running.tryAcquire()) {
-         // already running
-         return;
-      }
-
-      // we are not using any Thread Pool or any Scheduled Executors from the ArtemisServer
-      // as that would defeat the purpose,
-      // as in any deadlocks the schedulers may be starving for something not responding fast enough
-      thread = new Thread("Artemis Critical Analyzer") {
-         @Override
-         public void run() {
-            try {
-               while (true) {
-                  if (running.tryAcquire(getCheckTimeNanoSeconds(), TimeUnit.NANOSECONDS)) {
-                     running.release();
-                     // this means that the server has been stopped as we could acquire the semaphore... returning now
-                     break;
-                  }
-                  logger.trace("Checking critical analyzer");
-                  check();
-               }
-            } catch (InterruptedException interrupted) {
-               // i will just leave on that case
-            }
-         }
-      };
-
-      thread.setDaemon(true);
-
-      thread.start();
    }
 
    @Override
    public void stop() {
-      if (!isStarted()) {
+      scheduledComponent.stop();
-         // already stopped, leaving
-         return;
-      }
-
-      running.release();
-
-      try {
-         if (thread != null) {
-            thread.join();
-         }
-      } catch (Throwable e) {
-         logger.warn(e.getMessage(), e);
-      }
    }
 
    @Override
    public boolean isStarted() {
-      return running.availablePermits() == 0;
+      return scheduledComponent.isStarted();
    }
 }

artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/ActiveMQServerImpl.java

@@ -507,6 +507,8 @@ public class ActiveMQServerImpl implements ActiveMQServer {
 
       configuration.parseSystemProperties();
 
+      initializeExecutorServices();
+
       initializeCriticalAnalyzer();
 
       startDate = new Date();
@@ -575,13 +577,14 @@ public class ActiveMQServerImpl implements ActiveMQServer {
    private void initializeCriticalAnalyzer() throws Exception {
       if (analyzer == null) {
          if (configuration.isCriticalAnalyzer()) {
+            // this will have its own ScheduledPool
             this.analyzer = new CriticalAnalyzerImpl();
          } else {
             this.analyzer = EmptyCriticalAnalyzer.getInstance();
          }
       }
 
-      /** Calling this for cases where the server was stopped and now is being restarted... failback, etc...*/
+      /* Calling this for cases where the server was stopped and now is being restarted... failback, etc...*/
       this.analyzer.clear();
 
       this.getCriticalAnalyzer().setCheckTime(configuration.getCriticalAnalyzerCheckPeriod(), TimeUnit.MILLISECONDS).setTimeout(configuration.getCriticalAnalyzerTimeout(), TimeUnit.MILLISECONDS);
@@ -1181,9 +1184,11 @@ public class ActiveMQServerImpl implements ActiveMQServer {
       }
 
       try {
-         this.getCriticalAnalyzer().stop();
+         this.analyzer.stop();
       } catch (Exception e) {
          logger.warn(e.getMessage(), e);
+      } finally {
+         this.analyzer = null;
       }
 
       if (identity != null) {
@@ -2257,9 +2262,6 @@ public class ActiveMQServerImpl implements ActiveMQServer {
       if (state == SERVER_STATE.STOPPED)
          return false;
 
-      // Create the pools - we have two pools - one for non scheduled - and another for scheduled
-      initializeExecutorServices();
-
       if (configuration.getJournalType() == JournalType.ASYNCIO) {
          if (!AIOSequentialFileFactory.isSupported()) {
             ActiveMQServerLogger.LOGGER.switchingNIO();