Here’s a microbenchmark of SynchronizedRandomAccessList and CopyOnWriteArrayList. I wanted to see how well one or another performed with little number of changed, where CopyOnWriteArrayList could potentially be better.

package com.icyrock.java.collection; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.concurrent.CopyOnWriteArrayList; import java.util.concurrent.atomic.AtomicLong; public class SpeedPrb { private static interface ListCreator<I> { List<Integer> create(List<Integer> seed); } public static void main(String[] args) { new SpeedPrb().run(); } private void run() { try { runUnsafe(); } catch (Exception e) { e.printStackTrace(); } } private void runUnsafe() throws InterruptedException { for (String runType : new String[] { "warm-up", "test" }) { System.out.println("Run type: " + runType); withList(new ListCreator<List<Integer>>() { public List<Integer> create(List<Integer> seed) { return Collections.synchronizedList(new ArrayList<Integer>(seed)); } }); withList(new ListCreator<List<Integer>>() { public List<Integer> create(List<Integer> seed) { return new CopyOnWriteArrayList<Integer>(seed); } }); } } private void withList(ListCreator<List<Integer>> listCreator) throws InterruptedException { withThreadCount(listCreator, 1); withThreadCount(listCreator, 5); withThreadCount(listCreator, 10); } private void withThreadCount(ListCreator<List<Integer>> listCreator, int threadCount) throws InterruptedException { withDataSize(listCreator, threadCount, 10000); withDataSize(listCreator, threadCount, 100000); withDataSize(listCreator, threadCount, 1000000); } private void withDataSize(ListCreator<List<Integer>> listCreator, int threadCount, int dataSize) throws InterruptedException { withDataModSize(listCreator, threadCount, dataSize, 0); withDataModSize(listCreator, threadCount, dataSize, 1); withDataModSize(listCreator, threadCount, dataSize, 5); withDataModSize(listCreator, threadCount, dataSize, 10); withDataModSize(listCreator, threadCount, dataSize, 50); } private void withDataModSize(final ListCreator<List<Integer>> listCreator, final int threadCount, final int dataSize, final int dataModSize) throws InterruptedException { List<Integer> seed = new ArrayList<>(); for (int i = 0; i < dataSize; i++) { seed.add(i); } List<Integer> list = listCreator.create(seed); long start = System.nanoTime(); doMods(list, threadCount, dataSize, dataModSize); long sum = doSum(list, threadCount, dataSize); long end = System.nanoTime(); double elapsed = (end - start) / 1e6; System.out.println("End" + ": list.class: " + list.getClass().getSimpleName() + ", threadCount: " + threadCount + ", dataSize: " + dataSize + ", dataModSize: " + dataModSize + ", elapsed: " + elapsed + ", sum: " + sum); } private void doMods(final List<Integer> list, final int threadCount, final int dataSize, final int dataModSize) throws InterruptedException { Thread[] threads = new Thread[threadCount]; final int count = dataSize / threadCount; for (int i = 0; i < threadCount; i++) { final int modId = i * count; Thread thread = new Thread(new Runnable() { public void run() { int modCnt = 0; for (int i = 0; i < count; i++) { if (modCnt < dataModSize) { int pos = list.get(modId + i); list.set(pos, list.get(pos) + 1); modCnt++; } if (modCnt == dataModSize) { break; } } } }); thread.setDaemon(true); threads[i] = thread; } for (int i = 0; i < threadCount; i++) { threads[i].start(); } for (int i = 0; i < threadCount; i++) { Thread thread = threads[i]; synchronized (thread) { if (thread.isAlive()) { thread.wait(); } } } } private long doSum(final List<Integer> list, final int threadCount, final int dataSize) throws InterruptedException { final AtomicLong sum = new AtomicLong(); Thread[] threads = new Thread[threadCount]; final int count = dataSize / threadCount; for (int i = 0; i < threadCount; i++) { final int modId = i * count; Thread thread = new Thread(new Runnable() { public void run() { for (int i = 0; i < count; i++) { int pos = list.get(modId + i); long delta = list.get(pos); sum.addAndGet(delta); } } }); thread.setDaemon(true); threads[i] = thread; } for (int i = 0; i < threadCount; i++) { threads[i].start(); } for (int i = 0; i < threadCount; i++) { Thread thread = threads[i]; synchronized (thread) { if (thread.isAlive()) { thread.wait(); } } } return sum.get(); } }

Results:

Run type: warm-up End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 34.447801, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 1, elapsed: 8.95851, sum: 49995001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 5, elapsed: 9.545876, sum: 49995009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 10, elapsed: 1.744018, sum: 49995019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 50, elapsed: 1.887545, sum: 49995099 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 0, elapsed: 10.752156, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 1, elapsed: 13.370241, sum: 4999950001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 5, elapsed: 15.297022, sum: 4999950009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 10, elapsed: 10.267383, sum: 4999950019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 50, elapsed: 16.844115, sum: 4999950099 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 0, elapsed: 74.83112, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 1, elapsed: 82.226897, sum: 499999500001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 5, elapsed: 74.646764, sum: 499999500009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 10, elapsed: 71.52722, sum: 499999500019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 50, elapsed: 73.328613, sum: 499999500099 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 0, elapsed: 7.449299, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 1, elapsed: 7.883584, sum: 49995005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 5, elapsed: 7.536815, sum: 49995045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 10, elapsed: 7.7768, sum: 49995095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 50, elapsed: 9.246285, sum: 49995495 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 0, elapsed: 67.314426, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 1, elapsed: 70.664588, sum: 4999950005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 5, elapsed: 68.318753, sum: 4999950045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 10, elapsed: 71.206388, sum: 4999950095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 50, elapsed: 65.248959, sum: 4999950495 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 0, elapsed: 461.098965, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 1, elapsed: 406.9108, sum: 499999500005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 5, elapsed: 513.206703, sum: 499999500045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 10, elapsed: 473.542246, sum: 499999500095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 50, elapsed: 570.581461, sum: 499999500495 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 12.406631, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 1, elapsed: 14.833395, sum: 49995010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 5, elapsed: 11.98533, sum: 49995090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 10, elapsed: 11.679525, sum: 49995190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 50, elapsed: 13.218288, sum: 49995990 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 0, elapsed: 69.624681, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 1, elapsed: 69.140069, sum: 4999950010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 5, elapsed: 77.640096, sum: 4999950090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 10, elapsed: 71.927987, sum: 4999950190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 50, elapsed: 66.570783, sum: 4999950990 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 0, elapsed: 378.502667, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 1, elapsed: 419.156151, sum: 499999500010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 5, elapsed: 339.901594, sum: 499999500090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 10, elapsed: 426.555234, sum: 499999500190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 395.766989, sum: 499999500990 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 11.901218, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 1, elapsed: 3.829014, sum: 49995001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 5, elapsed: 10.980387, sum: 49995009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 10, elapsed: 1.90118, sum: 49995019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 50, elapsed: 5.033604, sum: 49995099 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 0, elapsed: 4.303462, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 1, elapsed: 6.433356, sum: 4999950001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 5, elapsed: 8.015953, sum: 4999950009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 10, elapsed: 10.697569, sum: 4999950019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 50, elapsed: 20.900689, sum: 4999950099 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 0, elapsed: 22.107373, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 1, elapsed: 26.153887, sum: 499999500001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 5, elapsed: 34.408805, sum: 499999500009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 10, elapsed: 51.090004, sum: 499999500019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 50, elapsed: 153.929584, sum: 499999500099 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 0, elapsed: 3.918603, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 1, elapsed: 5.118304, sum: 49995005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 5, elapsed: 8.821934, sum: 49995045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 10, elapsed: 12.317311, sum: 49995095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 50, elapsed: 21.752215, sum: 49995495 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 0, elapsed: 40.760553, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 1, elapsed: 27.017787, sum: 4999950005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 5, elapsed: 24.395766, sum: 4999950045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 10, elapsed: 39.489004, sum: 4999950095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 50, elapsed: 113.153861, sum: 4999950495 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 0, elapsed: 353.752201, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 1, elapsed: 282.50961, sum: 499999500005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 5, elapsed: 423.664369, sum: 499999500045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 10, elapsed: 501.767616, sum: 499999500095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 50, elapsed: 1458.115879, sum: 499999500495 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 6.227392, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 1, elapsed: 27.889835, sum: 49995010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 5, elapsed: 5.488267, sum: 49995090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 10, elapsed: 9.8526, sum: 49995190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 50, elapsed: 34.633951, sum: 49995990 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 0, elapsed: 44.695707, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 1, elapsed: 21.955976, sum: 4999950010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 5, elapsed: 54.120305, sum: 4999950090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 10, elapsed: 78.413631, sum: 4999950190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 50, elapsed: 239.205075, sum: 4999950990 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 0, elapsed: 362.92385, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 1, elapsed: 320.027424, sum: 499999500010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 5, elapsed: 505.38798, sum: 499999500090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 10, elapsed: 1165.81135, sum: 499999500190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 1869.912839, sum: 499999500990 Run type: test End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 0.97632, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 1, elapsed: 0.95858, sum: 49995001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 5, elapsed: 0.979087, sum: 49995009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 10, elapsed: 1.088347, sum: 49995019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 50, elapsed: 1.278052, sum: 49995099 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 0, elapsed: 5.128055, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 1, elapsed: 5.959685, sum: 4999950001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 5, elapsed: 6.951121, sum: 4999950009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 10, elapsed: 8.605555, sum: 4999950019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 100000, dataModSize: 50, elapsed: 3.878474, sum: 4999950099 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 0, elapsed: 34.628495, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 1, elapsed: 33.505706, sum: 499999500001 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 5, elapsed: 34.152629, sum: 499999500009 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 10, elapsed: 34.661612, sum: 499999500019 End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 1000000, dataModSize: 50, elapsed: 33.869828, sum: 499999500099 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 0, elapsed: 7.829228, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 1, elapsed: 7.338248, sum: 49995005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 5, elapsed: 6.597094, sum: 49995045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 10, elapsed: 9.179939, sum: 49995095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 10000, dataModSize: 50, elapsed: 12.672502, sum: 49995495 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 0, elapsed: 57.167164, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 1, elapsed: 57.412349, sum: 4999950005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 5, elapsed: 67.656372, sum: 4999950045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 10, elapsed: 63.353544, sum: 4999950095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 100000, dataModSize: 50, elapsed: 66.889391, sum: 4999950495 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 0, elapsed: 521.963095, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 1, elapsed: 517.867147, sum: 499999500005 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 5, elapsed: 542.079316, sum: 499999500045 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 10, elapsed: 386.976245, sum: 499999500095 End: list.class: SynchronizedRandomAccessList, threadCount: 5, dataSize: 1000000, dataModSize: 50, elapsed: 405.384225, sum: 499999500495 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 8.967124, sum: 49995000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 1, elapsed: 7.918772, sum: 49995010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 5, elapsed: 4.081412, sum: 49995090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 10, elapsed: 4.461432, sum: 49995190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 50, elapsed: 6.415205, sum: 49995990 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 0, elapsed: 45.251236, sum: 4999950000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 1, elapsed: 47.764752, sum: 4999950010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 5, elapsed: 60.124809, sum: 4999950090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 10, elapsed: 48.346995, sum: 4999950190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 100000, dataModSize: 50, elapsed: 39.349112, sum: 4999950990 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 0, elapsed: 340.371111, sum: 499999500000 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 1, elapsed: 481.969672, sum: 499999500010 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 5, elapsed: 535.011974, sum: 499999500090 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 10, elapsed: 540.011967, sum: 499999500190 End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 531.670146, sum: 499999500990 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 1.149342, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 1, elapsed: 1.239204, sum: 49995001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 5, elapsed: 1.352173, sum: 49995009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 10, elapsed: 1.7898, sum: 49995019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 10000, dataModSize: 50, elapsed: 3.165936, sum: 49995099 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 0, elapsed: 5.357431, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 1, elapsed: 6.688772, sum: 4999950001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 5, elapsed: 8.353105, sum: 4999950009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 10, elapsed: 10.515936, sum: 4999950019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 100000, dataModSize: 50, elapsed: 20.277377, sum: 4999950099 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 0, elapsed: 23.185615, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 1, elapsed: 27.466323, sum: 499999500001 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 5, elapsed: 33.748808, sum: 499999500009 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 10, elapsed: 48.301544, sum: 499999500019 End: list.class: CopyOnWriteArrayList, threadCount: 1, dataSize: 1000000, dataModSize: 50, elapsed: 198.997429, sum: 499999500099 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 0, elapsed: 5.603725, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 1, elapsed: 6.166289, sum: 49995005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 5, elapsed: 7.827472, sum: 49995045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 10, elapsed: 9.659996, sum: 49995095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 10000, dataModSize: 50, elapsed: 20.942762, sum: 49995495 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 0, elapsed: 40.315674, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 1, elapsed: 42.313047, sum: 4999950005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 5, elapsed: 38.214826, sum: 4999950045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 10, elapsed: 42.748483, sum: 4999950095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 100000, dataModSize: 50, elapsed: 111.678623, sum: 4999950495 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 0, elapsed: 271.684979, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 1, elapsed: 285.626939, sum: 499999500005 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 5, elapsed: 382.996082, sum: 499999500045 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 10, elapsed: 469.095528, sum: 499999500095 End: list.class: CopyOnWriteArrayList, threadCount: 5, dataSize: 1000000, dataModSize: 50, elapsed: 1126.529645, sum: 499999500495 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 5.903503, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 1, elapsed: 5.537715, sum: 49995010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 5, elapsed: 8.679113, sum: 49995090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 10, elapsed: 13.175054, sum: 49995190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 50, elapsed: 27.420182, sum: 49995990 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 0, elapsed: 37.46934, sum: 4999950000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 1, elapsed: 21.53966, sum: 4999950010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 5, elapsed: 54.847308, sum: 4999950090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 10, elapsed: 56.360711, sum: 4999950190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 100000, dataModSize: 50, elapsed: 191.754104, sum: 4999950990 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 0, elapsed: 333.820706, sum: 499999500000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 1, elapsed: 398.443131, sum: 499999500010 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 5, elapsed: 547.40548, sum: 499999500090 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 10, elapsed: 757.341745, sum: 499999500190 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 2268.404341, sum: 499999500990

This was done on AMD Phenom II X4 Mobile N950, 2.1 GHz, which has 4 cores.

Comments:

- Modifications hurt CopyOnWriteArrayList, especially with big data sizes – even only 50 modifications make it 4 times slower

End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 531.670146, sum: 499999500990 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 1000000, dataModSize: 50, elapsed: 2268.404341, sum: 499999500990

- Without modifications, SynchronizedRandomAccessList pays the price for having to do synchronization being 70%-80% slower:

End: list.class: SynchronizedRandomAccessList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 8.967124, sum: 49995000 End: list.class: CopyOnWriteArrayList, threadCount: 10, dataSize: 10000, dataModSize: 0, elapsed: 5.903503, sum: 49995000

- Warm-up is really important when measuring – here we see a 35 times slower run:

Run type: warm-up End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 34.447801, sum: 49995000 ... Run type: test End: list.class: SynchronizedRandomAccessList, threadCount: 1, dataSize: 10000, dataModSize: 0, elapsed: 0.97632, sum: 49995000

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