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Date: Fri, 21 Aug 2009 17:24:01 +0800
Message-ID: <797beb000908210224g7ff6a6d0h82e61b4dfbac490@mail.gmail.com>
Subject: Re: Possible concurrency bug with Workspace.copy() ?
From: Jervis Liu <jervisliu@gmail.com>
To: users@jackrabbit.apache.org
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Done: https://issues.apache.org/jira/browse/JCR-2269.

Thanks,
Jervis


2009/8/21 Stefan Guggisberg <stefan.guggisberg@gmail.com>:
> hi jervis
>
> On Fri, Aug 21, 2009 at 5:41 AM, Jervis Liu<jervisliu@gmail.com> wrote:
>> Hi,
>>
>> Enclosed below is a test case that can be used to reproduce a
>> concurrency bug. This test case uses two con-current threads to
>> execute Workspace.copy() to copy a node to same destination. The
>> parent node has set its allowSameNameSiblings to false. According to
>> the javadoc of Workspace.copy(String srcAbsPath, String destAbsPath) :
>> "This method copies the node at srcAbsPath to the new location at
>> destAbsPath. If successful, the change is persisted immediately, there
>> is no need to call save.". =A0"An ItemExistException is thrown if a
>> property already exists at destAbsPath or a node already exist there,
>> and same name siblings are not allowed. "
>>
>> However in reality this is not the case. =A0The test case can end up
>> with two child nodes with same names. Please note, not every run can
>> reproduce the problem, but generally I can get the problem within 3 to
>> 10 iterations. I also got an InvalidItemStateException once (only
>> once). =A0Can someone kindly help to confirm if this is a bug in
>> Jackrabbit or maybe I am using JackRabbit in a wrong way? The test
>> case has been tested on Jackrabbit 1.6 branch
>> (http://svn.apache.org/repos/asf/jackrabbit/tags/1.6.0), Windows
>> Vista, JDK 1.5.0_14.
>
> this definitely smells like a bug. do you mind posting a jira issue?
>
> thanks!
> stefan
>
>>
>> The test case is also attached for your convenience.
>>
>> Thanks,
>> Jervis Liu
>>
>> package org.apache.jackrabbit.core;
>>
>> import org.apache.jackrabbit.test.AbstractJCRTest;
>> import javax.jcr.ItemExistsException;
>> import javax.jcr.Node;
>> import javax.jcr.Session;
>> import javax.jcr.Value;
>> import javax.jcr.NodeIterator;
>> import java.util.Random;
>> import java.util.ArrayList;
>> import java.util.Iterator;
>> import javax.jcr.nodetype.NodeType;
>>
>> import org.apache.jackrabbit.test.NotExecutableException;
>> import javax.jcr.RepositoryException;
>> import javax.jcr.nodetype.NodeTypeManager;
>>
>>
>> public class ConcurrentCopyTest extends AbstractJCRTest {
>>
>> =A0 =A0private static final int NUM_ITERATIONS =3D 40;
>> =A0 =A0private static final int NUM_SESSIONS =3D 2;
>>
>> =A0 =A0String sourcePath;
>> =A0 =A0String destPath;
>>
>> =A0 =A0public void testConcurrentCopy() throws Exception {
>> =A0 =A0 =A0 =A0for (int n =3D 0; n < NUM_ITERATIONS; n++) {
>> =A0 =A0 =A0 =A0 =A0 =A0System.out.println("---Iteration---- " + n);
>>
>> =A0 =A0 =A0 =A0 =A0 =A0// clean up testRoot first
>> =A0 =A0 =A0 =A0 =A0 =A0if (testRootNode.hasNode("ConcurrentCopyTestNode"=
)) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Node testNode =3D testRootNode.getNode("C=
oncurrentCopyTestNode");
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0testNode.remove();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0testRootNode.save();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0System.out.println("---old node removed--=
-");
>> =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0 =A0 =A0// create a parent node where allowSameNameSiblin=
gs is set to false
>> =A0 =A0 =A0 =A0 =A0 =A0Node snsfNode =3D testRootNode.addNode("Concurren=
tCopyTestNode",
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0"nt:folder");
>> =A0 =A0 =A0 =A0 =A0 =A0testRootNode.save();
>> =A0 =A0 =A0 =A0 =A0 =A0sourcePath =3D snsfNode.getPath();
>> =A0 =A0 =A0 =A0 =A0 =A0destPath =3D sourcePath + "/" + "CopiedFromConcur=
rentCopyTestNode";
>> =A0 =A0 =A0 =A0 =A0 =A0System.out.println("---sourcePath----------------=
-" + sourcePath);
>> =A0 =A0 =A0 =A0 =A0 =A0System.out.println("---destPath-----------------"=
 + destPath);
>>
>> =A0 =A0 =A0 =A0 =A0 =A0// firstly we verify it works with single thread.
>> =A0 =A0 =A0 =A0 =A0 =A0Session rootSession =3D helper.getSuperuserSessio=
n();
>> =A0 =A0 =A0 =A0 =A0 =A0rootSession.getWorkspace().copy(sourcePath, destP=
ath + "test");
>>
>> =A0 =A0 =A0 =A0 =A0 =A0// copy again to same destPath, expect an ItemExi=
stsException
>> =A0 =A0 =A0 =A0 =A0 =A0try {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0rootSession.getWorkspace().copy(sourcePat=
h, destPath + "test");
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0fail("Node exists below '" + destPath + "=
'. Test should fail.");
>> =A0 =A0 =A0 =A0 =A0 =A0} catch (ItemExistsException e) {
>> =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0 =A0 =A0Thread[] threads =3D new Thread[NUM_SESSIONS];
>> =A0 =A0 =A0 =A0 =A0 =A0for (int i =3D 0; i < threads.length; i++) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0// create new session
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Session session =3D helper.getSuperuserSe=
ssion();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0TestSession ts =3D new TestSession("s" + =
i, session);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Thread t =3D new Thread(ts);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0t.setName((NUM_ITERATIONS - n) + "-s" + i=
);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0t.start();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0log.println("Thread#" + i + " started");
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0threads[i] =3D t;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0// Thread.yield();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0// Thread.sleep(100);
>> =A0 =A0 =A0 =A0 =A0 =A0}
>> =A0 =A0 =A0 =A0 =A0 =A0for (int i =3D 0; i < threads.length; i++) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0threads[i].join();
>> =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0 =A0 =A0NodeIterator results =3D testRootNode.getNode(
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0"ConcurrentCopyTestNode").getNode=
s(
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0"CopiedFromConcurrentCopyTestNode=
");
>> =A0 =A0 =A0 =A0 =A0 =A0while (results.hasNext()) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Node node =3D results.nextNode();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0System.out.println("--result node- " + no=
de.getName());
>> =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0 =A0 =A0assertEquals(1, results.getSize());
>> =A0 =A0 =A0 =A0}
>> =A0 =A0}
>>
>> =A0 =A0// --------------------------------------------------------< inne=
r classes >
>> =A0 =A0class TestSession implements Runnable {
>>
>> =A0 =A0 =A0 =A0Session session;
>> =A0 =A0 =A0 =A0String identity;
>> =A0 =A0 =A0 =A0Random r;
>>
>> =A0 =A0 =A0 =A0TestSession(String identity, Session s) {
>> =A0 =A0 =A0 =A0 =A0 =A0session =3D s;
>> =A0 =A0 =A0 =A0 =A0 =A0this.identity =3D identity;
>> =A0 =A0 =A0 =A0 =A0 =A0r =3D new Random();
>> =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0private void randomSleep() {
>> =A0 =A0 =A0 =A0 =A0 =A0long l =3D r.nextInt(90) + 20;
>> =A0 =A0 =A0 =A0 =A0 =A0try {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Thread.sleep(l);
>> =A0 =A0 =A0 =A0 =A0 =A0} catch (InterruptedException ie) {
>> =A0 =A0 =A0 =A0 =A0 =A0}
>> =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0public void run() {
>>
>> =A0 =A0 =A0 =A0 =A0 =A0log.println("started.");
>> =A0 =A0 =A0 =A0 =A0 =A0String state =3D "";
>> =A0 =A0 =A0 =A0 =A0 =A0try {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0this.session.getWorkspace().copy(sourcePa=
th, destPath);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0session.save();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Node newNode =3D
>> testRootNode.getNode("ConcurrentCopyTestNode/CopiedFromConcurrentCopyTes=
tNode");
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0System.out.println("--Added node- " + new=
Node.getName());
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0session.save();
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0randomSleep();
>> =A0 =A0 =A0 =A0 =A0 =A0} catch (Exception e) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0log.println("Exception while " + state + =
": " + e.getMessage());
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0e.printStackTrace();
>> =A0 =A0 =A0 =A0 =A0 =A0} finally {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0session.logout();
>> =A0 =A0 =A0 =A0 =A0 =A0}
>>
>> =A0 =A0 =A0 =A0 =A0 =A0log.println("ended.");
>> =A0 =A0 =A0 =A0}
>> =A0 =A0}
>>
>> }
>>
>