Author: markt
Date: Sun Sep 23 15:20:38 2012
New Revision: 1389076
URL: http://svn.apache.org/viewvc?rev=1389076&view=rev
Log:
ConcurrentLinkedQueue is currently the biggest contributor to garbage in the
load test so this is intended as a replacement.
Added:
tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java
(with props)
tomcat/trunk/test/org/apache/tomcat/util/collections/
tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java
(with props)
tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java
(with props)
Added: tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java?rev=1389076&view=auto
==============================================================================
--- tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java
(added)
+++ tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java
Sun Sep 23 15:20:38 2012
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.tomcat.util.collections;
+
+/**
+ * This is intended as a (mostly) GC-free alternative to
+ * {@link java.util.concurrent.LinkedBlockingDeque} where the requirement is to
+ * create a pool of re-usable objects with no requirement to shrink the pool.
+ * The aim is to provide the bare minimum of required functionality as quickly
+ * as possible with minimum garbage.
+ */
+public class ConcurrentStack<T> {
+
+ private int size = 128;
+ /*
+ * Points to the next available object in the stack
+ */
+ private int index = -1;
+
+ private Object[] stack = new Object[size];
+
+ public synchronized void push(T obj) {
+ index++;
+ if (index == size) {
+ expand();
+ }
+ stack[index] = obj;
+ }
+
+ @SuppressWarnings("unchecked")
+ public synchronized T pop() {
+ if (index == -1) {
+ return null;
+ }
+ return (T) stack[index--];
+ }
+
+ private void expand() {
+ int newSize = size * 2;
+ Object[] newStack = new Object[newSize];
+ System.arraycopy(stack, 0, newStack, 0, size);
+ // This is the only point where garbage is created by throwing away the
+ // old array. Note it is only the array, not the contents, that becomes
+ // garbage.
+ stack = newStack;
+ size = newSize;
+ }
+}
Propchange:
tomcat/trunk/java/org/apache/tomcat/util/collections/ConcurrentStack.java
------------------------------------------------------------------------------
svn:eol-style = native
Added:
tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java?rev=1389076&view=auto
==============================================================================
---
tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java
(added)
+++
tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java
Sun Sep 23 15:20:38 2012
@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.tomcat.util.collections;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestConcurrentStack {
+
+ @Test
+ public void testPopEmpty() {
+ ConcurrentStack<Object> stack = new ConcurrentStack<>();
+ Assert.assertNull(stack.pop());
+ }
+
+ @Test
+ public void testPushPopOrder() {
+ ConcurrentStack<Object> stack = new ConcurrentStack<>();
+
+ Object o1 = new Object();
+ Object o2 = new Object();
+ Object o3 = new Object();
+ Object o4 = new Object();
+
+ stack.push(o1);
+ stack.push(o2);
+ stack.push(o3);
+ stack.push(o4);
+
+ Assert.assertSame(stack.pop(), o4);
+ Assert.assertSame(stack.pop(), o3);
+ Assert.assertSame(stack.pop(), o2);
+ Assert.assertSame(stack.pop(), o1);
+
+ Assert.assertNull(stack.pop());
+ }
+
+ @Test
+ public void testExpandPushPopOrder() {
+ ConcurrentStack<Object> stack = new ConcurrentStack<>();
+
+ Object o1 = new Object();
+ Object o2 = new Object();
+ Object o3 = new Object();
+ Object o4 = new Object();
+
+ for (int i = 0; i < 300; i++) {
+ stack.push(o1);
+ stack.push(o2);
+ stack.push(o3);
+ stack.push(o4);
+ }
+
+ for (int i = 0; i < 300; i++) {
+ Assert.assertSame(stack.pop(), o4);
+ Assert.assertSame(stack.pop(), o3);
+ Assert.assertSame(stack.pop(), o2);
+ Assert.assertSame(stack.pop(), o1);
+ }
+
+ Assert.assertNull(stack.pop());
+ }
+
+}
Propchange:
tomcat/trunk/test/org/apache/tomcat/util/collections/TestConcurrentStack.java
------------------------------------------------------------------------------
svn:eol-style = native
Added:
tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java?rev=1389076&view=auto
==============================================================================
---
tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java
(added)
+++
tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java
Sun Sep 23 15:20:38 2012
@@ -0,0 +1,107 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.tomcat.util.collections;
+
+import java.util.Queue;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+import org.junit.Test;
+
+public class TesterPerformanceConcurrentStack {
+
+ private static final int THREAD_COUNT = 8;
+ private static final int ITERATIONS = 1000000;
+
+ private static final ConcurrentStack<Object> STACK =
+ new ConcurrentStack<>();
+
+ private static final Queue<Object> QUEUE = new ConcurrentLinkedQueue<>();
+
+ @Test
+ public void testConcurrentStack() throws InterruptedException {
+ Thread[] threads = new Thread[THREAD_COUNT];
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i] = new StackThread();
+ }
+
+ long start = System.currentTimeMillis();
+
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i].start();
+ }
+
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i].join();
+ }
+
+ long end = System.currentTimeMillis();
+
+ System.out.println("ConcurrentStack: " + (end - start) + "ms");
+ }
+
+ public static class StackThread extends Thread {
+
+ @Override
+ public void run() {
+ for(int i = 0; i < ITERATIONS; i++) {
+ Object obj = STACK.pop();
+ if (obj == null) {
+ obj = new Object();
+ }
+ STACK.push(obj);
+ }
+ super.run();
+ }
+ }
+
+ @Test
+ public void testConcurrentQueue() throws InterruptedException {
+ Thread[] threads = new Thread[THREAD_COUNT];
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i] = new QueueThread();
+ }
+
+ long start = System.currentTimeMillis();
+
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i].start();
+ }
+
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ threads[i].join();
+ }
+
+ long end = System.currentTimeMillis();
+
+ System.out.println("ConcurrentLinkedQueue: " + (end - start) + "ms");
+ }
+
+ public static class QueueThread extends Thread {
+
+ @Override
+ public void run() {
+ for(int i = 0; i < ITERATIONS; i++) {
+ Object obj = QUEUE.poll();
+ if (obj == null) {
+ obj = new Object();
+ }
+ QUEUE.add(obj);
+ }
+ super.run();
+ }
+ }
+}
Propchange:
tomcat/trunk/test/org/apache/tomcat/util/collections/TesterPerformanceConcurrentStack.java
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svn:eol-style = native
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