Bug:645 - MDSAL Notification pool threads not getting spawned besides the core threads

Change-Id: I6851f9b90b500b2b10a135bcda784a11c8f44786
Signed-off-by: Kamal Rameshan <kramesha@cisco.com>

diff --git a/opendaylight/md-sal/sal-binding-broker/src/main/java/org/opendaylight/controller/sal/binding/codegen/impl/SingletonHolder.java b/opendaylight/md-sal/sal-binding-broker/src/main/java/org/opendaylight/controller/sal/binding/codegen/impl/SingletonHolder.java
index 4deef69198216c5d0f6fe1578caccee90dbc1458..ac26445bf408677b6e397c9fbb77bcf4fcaa19de 100644 (file)
--- a/opendaylight/md-sal/sal-binding-broker/src/main/java/org/opendaylight/controller/sal/binding/codegen/impl/SingletonHolder.java
+++ b/opendaylight/md-sal/sal-binding-broker/src/main/java/org/opendaylight/controller/sal/binding/codegen/impl/SingletonHolder.java
@@ -7,22 +7,22 @@
  */
 package org.opendaylight.controller.sal.binding.codegen.impl;
 
+import com.google.common.util.concurrent.ListeningExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import javassist.ClassPool;
+import org.opendaylight.controller.sal.binding.codegen.RuntimeCodeGenerator;
+import org.opendaylight.controller.sal.binding.spi.NotificationInvokerFactory;
+
+import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionHandler;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
-import javassist.ClassPool;
-
-import org.opendaylight.controller.sal.binding.codegen.RuntimeCodeGenerator;
-import org.opendaylight.controller.sal.binding.spi.NotificationInvokerFactory;
-
-import com.google.common.util.concurrent.ListeningExecutorService;
-import com.google.common.util.concurrent.MoreExecutors;
-import com.google.common.util.concurrent.ThreadFactoryBuilder;
-
 public class SingletonHolder {
 
     public static final ClassPool CLASS_POOL = ClassPool.getDefault();
@@ -45,12 +45,43 @@ public class SingletonHolder {
      */
     @Deprecated
     public static synchronized final ListeningExecutorService getDefaultNotificationExecutor() {
+
         if (NOTIFICATION_EXECUTOR == null) {
+            // Overriding the queue since we need an unbounded queue
+            // and threadpoolexecutor would not create new threads if the queue is not full
+            BlockingQueue<Runnable> queue = new LinkedBlockingQueue<Runnable>() {
+                @Override
+                public boolean offer(Runnable r) {
+                    if (size() <= 1) {
+                        // if the queue is empty (or has just 1), no need to rampup the threads
+                        return super.offer(r);
+                    } else {
+                        // if the queue is not empty, force the queue to return false.
+                        // threadpoolexecutor will spawn a new thread if the queue.offer returns false.
+                        return false;
+                    }
+                }
+            };
+
             ThreadFactory factory = new ThreadFactoryBuilder().setDaemon(true).setNameFormat("md-sal-binding-notification-%d").build();
-            ExecutorService executor = new ThreadPoolExecutor(CORE_NOTIFICATION_THREADS, MAX_NOTIFICATION_THREADS,
-                    NOTIFICATION_THREAD_LIFE, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), factory);
+
+            ThreadPoolExecutor executor = new ThreadPoolExecutor(CORE_NOTIFICATION_THREADS, MAX_NOTIFICATION_THREADS,
+                    NOTIFICATION_THREAD_LIFE, TimeUnit.SECONDS, queue , factory,
+                    new RejectedExecutionHandler() {
+                        // if the max threads are met, then it will raise a rejectedExecution. We then push to the queue.
+                        @Override
+                        public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
+                            try {
+                                executor.getQueue().put(r);
+                            } catch (InterruptedException e) {
+                                e.printStackTrace();
+                            }
+                        }
+                    });
+
             NOTIFICATION_EXECUTOR = MoreExecutors.listeningDecorator(executor);
         }
+
         return NOTIFICATION_EXECUTOR;
     }