[
https://issues.apache.org/jira/browse/CAY-957?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andrus Adamchik updated CAY-957:
--------------------------------
Attachment: 0001-CAY-957-Deadlock-in-nested-contexts.patch
Here is a unit test against 3.1M3+ that demonstrates the deadlock. After
CAY-1653 fix cleared one deadlock, it now happens between parent and child
ObjectStores (a classic situation) -
"UpdateThread-1":
at
org.apache.cayenne.access.DataContextMergeHandler.graphChanged(DataContextMergeHandler.java:103)
- waiting to lock <7f4316d78> (a org.apache.cayenne.access.ObjectStore)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.cayenne.util.Invocation.fire(Invocation.java:202)
at
org.apache.cayenne.event.DefaultEventManager$Dispatch.fire(DefaultEventManager.java:400)
at
org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:162)
at
org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:65)
at
org.apache.cayenne.event.DefaultEventManager.dispatchEvent(DefaultEventManager.java:339)
at
org.apache.cayenne.event.DefaultEventManager.postEvent(DefaultEventManager.java:310)
at
org.apache.cayenne.BaseContext.fireDataChannelChanged(BaseContext.java:565)
at
org.apache.cayenne.access.DataContext.fireDataChannelChanged(DataContext.java:1194)
at
org.apache.cayenne.access.DataContext.onContextFlush(DataContext.java:770)
at org.apache.cayenne.BaseContext.onSync(BaseContext.java:516)
at
org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:816)
- locked <7f435cfe0> (a org.apache.cayenne.access.ObjectStore)
at
org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:755)
at
org.apache.cayenne.access.NestedDataContext_DeadlockTest$UpdateThread.run(NestedDataContext_DeadlockTest.java:121)
"UpdateThread-0":
at
org.apache.cayenne.access.DataContextMergeHandler.graphChanged(DataContextMergeHandler.java:103)
- waiting to lock <7f435cfe0> (a org.apache.cayenne.access.ObjectStore)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.cayenne.util.Invocation.fire(Invocation.java:202)
at
org.apache.cayenne.event.DefaultEventManager$Dispatch.fire(DefaultEventManager.java:400)
at
org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:162)
at
org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:65)
at
org.apache.cayenne.event.DefaultEventManager.dispatchEvent(DefaultEventManager.java:339)
at
org.apache.cayenne.event.DefaultEventManager.postEvent(DefaultEventManager.java:310)
at
org.apache.cayenne.BaseContext.fireDataChannelChanged(BaseContext.java:565)
at
org.apache.cayenne.access.DataContext.fireDataChannelChanged(DataContext.java:1194)
at
org.apache.cayenne.access.DataContext.onContextFlush(DataContext.java:770)
at org.apache.cayenne.BaseContext.onSync(BaseContext.java:516)
at
org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:816)
- locked <7f4316d78> (a org.apache.cayenne.access.ObjectStore)
at
org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:755)
at
org.apache.cayenne.access.NestedDataContext_DeadlockTest$UpdateThread.run(NestedDataContext_DeadlockTest.java:121)
Found 1 deadlock.
> Deadlock in nested contexts
> ---------------------------
>
> Key: CAY-957
> URL: https://issues.apache.org/jira/browse/CAY-957
> Project: Cayenne
> Issue Type: Bug
> Components: Core Library
> Affects Versions: 1.2 branch, 2.0 branch, 3.0
> Reporter: Andrus Adamchik
> Assignee: Andrus Adamchik
> Fix For: Short term future
>
> Attachments: 0001-CAY-957-Deadlock-in-nested-contexts.patch
>
>
> There is a deadlock condition when two peer nested contexts commit
> simultaneously. Here is a small test case:
> package org.test;
> import java.util.Date;
> import java.util.List;
> import java.util.Random;
> import org.apache.cayenne.access.DataContext;
> import org.apache.cayenne.query.EJBQLQuery;
> public class Main {
> public static void main(String[] args) {
> DataContext parent = DataContext.createDataContext();
> parent.performGenericQuery(new EJBQLQuery("delete from
> Artist"));
> for (int i = 0; i < 300; i++) {
> Artist a = parent.newObject(Artist.class);
> a.setArtistName("X" + i);
> a.setDateOfBirth(new Date());
> }
> parent.commitChanges();
> Random rnd = new Random(System.currentTimeMillis());
> for (int i = 0; i < 2; i++) {
> new UpdateThread(parent.createChildDataContext(),
> rnd).start();
> }
> synchronized (parent) {
> try {
> parent.wait();
> } catch (InterruptedException e) {
> // TODO Auto-generated catch block
> e.printStackTrace();
> }
> }
> }
> static class UpdateThread extends Thread {
> protected DataContext context;
> protected Random rnd;
> UpdateThread(DataContext context, Random rnd) {
> super("UpdateThread-" + context.hashCode());
> setDaemon(true);
> this.context = context;
> this.rnd = rnd;
> }
> @Override
> public void run() {
> List<Artist> artists = context.performQuery(new
> EJBQLQuery(
> "select a FROM Artist a"));
> for (int i = 0; i < 1000; i++) {
> for (int j = 0; j < 5; j++) {
> int index = rnd.nextInt(artists.size());
> Artist a = artists.get(index);
> a.setArtistName("Y" + rnd.nextInt());
> }
> context.commitChanges();
> System.out.println(getId() + ": " + i);
> }
> }
> }
> }
> It deadlocks almost immediately with only two threads... Here is the stacks
> from Jconsole:
> Name: UpdateThread-9684455
> State: BLOCKED on org.apache.cayenne.event.DispatchQueue@f899e9 owned by:
> UpdateThread-10872036
> Total blocked: 7 Total waited: 1
> Stack trace:
> org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:54)
> org.apache.cayenne.event.EventManager.dispatchEvent(EventManager.java:348)
> org.apache.cayenne.event.EventManager.postEvent(EventManager.java:319)
> org.apache.cayenne.access.DataContext.fireDataChannelChanged(DataContext.java:1457)
> org.apache.cayenne.access.DataContext.onContextFlush(DataContext.java:1121)
> org.apache.cayenne.access.DataContext.onSync(DataContext.java:1102)
> org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:1160)
> org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:1073)
> org.test.Main$UpdateThread.run(Main.java:66)
> Name: UpdateThread-10872036
> State: BLOCKED on org.apache.cayenne.access.ObjectStore@1b9b03 owned by:
> UpdateThread-9684455
> Total blocked: 9 Total waited: 0
> Stack trace:
> org.apache.cayenne.access.DataContextMergeHandler.graphChanged(DataContextMergeHandler.java:104)
> sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> java.lang.reflect.Method.invoke(Method.java:585)
> org.apache.cayenne.util.Invocation.fire(Invocation.java:204)
> org.apache.cayenne.event.EventManager$Dispatch.fire(EventManager.java:409)
> org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:162)
> org.apache.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:58)
> org.apache.cayenne.event.EventManager.dispatchEvent(EventManager.java:348)
> org.apache.cayenne.event.EventManager.postEvent(EventManager.java:319)
> org.apache.cayenne.access.DataContext.fireDataChannelChanged(DataContext.java:1457)
> org.apache.cayenne.access.DataContext.onContextFlush(DataContext.java:1121)
> org.apache.cayenne.access.DataContext.onSync(DataContext.java:1102)
> org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:1160)
> org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:1073)
> org.test.Main$UpdateThread.run(Main.java:66)
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