[#NUCCORE-234] Multithreaded PersistenceManagerFactory still ConcurrentModificationException when getting FetchGroup - DataNucleus JIRA

DataNucleus Core

Multithreaded PersistenceManagerFactory still ConcurrentModificationException when getting FetchGroup

Created: 30/Mar/09 07:25 PM Updated: 26/Apr/10 03:37 PM Resolved: 19/Apr/10 08:39 AM

Component/s:

JDO

Affects Version/s:

1.1.1

Fix Version/s:

2.1.0.m2

File Attachments:	1. NUCCORE-234-core.patch (7 kB)
Environment:	Linux, Java 5 & 6

Forum Thread URL:	HTTP://WWW.JPOx.org/servlet/forum/viewthread_thread,5405
Datastore:	IBM DB2
Severity:	Production

Description

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Thanks a lot to Erik for having fixed HTTP://WWW.JPOx.org/servlet/jira/browse/NUCCORE-170 in 1.1.1. No more ConcurrentModificationException for removeFetchGroup & addFetchGroup. However, there're some for getFetchGroup now:

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:1036)
at java.util.HashMap$KeyIterator.next(HashMap.java:1073)
at org.datanucleus.jdo.JDOPersistenceManagerFactory.getFetchGroup(JDOPersistenceManagerFactory.java:1783)

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Peter Dettman added a comment - 19/Apr/10 06:55 AM

Proposed patch against 'core' project:

1. Changes to JDOPersistenceManagerFactory to fix race conditions around access to 'jdoFetchGroups' field.

2. Fix for FetchGroupManagerTest.testMultithreadedAccess, which intermittently fails for reasons internal to the test case itself.

3. JDOPersistenceManagerFactory.getFetchGroups changed to conform to API by returning a mutable copy of the fetch groups.

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Peter Dettman added a comment - 19/Apr/10 06:58 AM

Re-upload as project-relative patch

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Peter Dettman added a comment - 19/Apr/10 07:40 AM

Updated patch to include:

4. Add synchronized keyword to ObjectManagerFactoryImpl.getFetchGroupManager

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Andy Jefferson added a comment - 19/Apr/10 08:39 AM

Thx for the patch. Applied to SVN trunk apart from the part that set "jdoFetchGroups" on initialisation; need to keep a PMF as small as possible and most use-cases won't have any fetch groups defined dynamically. Also completed one TODO in the patch in PMF.close().

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