Added a Stop() method to handle stopping executor worker threads.

fix for bug 1181569

Refactored how stop was handled.  Removing thread and stopping thread
in the same syncronized loop was causing concurrent modification error.
Needed to seperate the actions for it to work.

Change-Id: I99b676f377842826f9e6a847cfeff76be91c8299

src/main/java/hudson/plugins/gearman/AbstractWorkerThread.java

@@ -20,12 +20,9 @@
 
 import java.util.Date;
 import java.util.Set;
-import java.util.HashSet;
 
-import org.gearman.worker.GearmanFunctionFactory;
 import org.gearman.common.GearmanNIOJobServerConnection;
-import org.gearman.worker.GearmanWorker;
-//import org.gearman.worker.GearmanWorkerImpl;
+import org.gearman.worker.GearmanFunctionFactory;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -118,8 +115,7 @@ public void stop() {
 
         if (worker.isRunning()) {
             try {
-                logger.info("---- Stopping " + getName() +" (" + new Date().toString() + ")");
-                worker.shutdown();
+                worker.stop();
             } catch (Exception e) {
                 e.printStackTrace();
             }

src/main/java/hudson/plugins/gearman/ComputerListenerImpl.java

@@ -23,7 +23,6 @@
 import hudson.slaves.ComputerListener;
 
 import java.io.IOException;
-import java.util.List;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -67,19 +66,8 @@ public void onOffline(Computer c) {
             return;
         }
 
-        // remove worker when jenkins slave is deleted or disconnected
-        GearmanProxy gp = GearmanProxy.getInstance();
-        List<AbstractWorkerThread> workers = gp.getGewtHandles();
-        synchronized(workers) {
-            for (AbstractWorkerThread worker : workers) {
-                if (worker.name.contains(c.getName())) {
-                    logger.info("---- stopping executor worker = "
-                              + worker.getName());
-                    gp.getGewtHandles().remove(worker);
-                    worker.stop();
-                }
-            }
-        }
+        // stop worker when jenkins slave is deleted or disconnected
+        GearmanProxy.getInstance().stop(c);
     }
 
     @Override

src/main/java/hudson/plugins/gearman/GearmanProxy.java

@@ -23,6 +23,7 @@
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Iterator;
 import java.util.List;
 
 import jenkins.model.Jenkins;
@@ -142,6 +143,9 @@ public void createManagementWorker() {
                 masterName);
         gwt.start();
         gmwtHandles.add(gwt);
+
+        logger.info("---- Num of executors running = " + getNumExecutors());
+
     }
 
     /*
@@ -168,8 +172,10 @@ public void createExecutorWorkersOnNode(Computer computer) {
             //ewt.registerJobs();
             ewt.start();
             gewtHandles.add(ewt);
-
         }
+
+        logger.info("---- Num of executors running = " + getNumExecutors());
+
     }
 
     /*
@@ -194,6 +200,31 @@ public void stopAll() {
         logger.info("---- Num of executors running = " + getNumExecutors());
     }
 
+    /*
+     * This method stops all threads on the gewtHandles list that
+     * is used to  service the jenkins slave/computer
+     *
+     *
+     * @param Node
+     *      The Computer to stop
+     *
+     */
+    public void stop(Computer computer) {
+
+        // find the computer in the executor workers list and stop it
+        synchronized(gewtHandles) {
+            for (Iterator<AbstractWorkerThread> it = gewtHandles.iterator(); it.hasNext(); ) {
+                AbstractWorkerThread t = it.next();
+                if (t.name.contains(computer.getName())) {
+                    t.stop();
+                    it.remove();
+                }
+             }
+        }
+
+        logger.info("---- Num of executors running = " + getNumExecutors());
+    }
+
     /*
      * This method returns the total number of gearman executor threads
      */