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Key: NUCCORE-559
Type: Bug Bug
Status: Closed Closed
Resolution: Fixed
Priority: Major Major
Assignee: Erik Bengtson
Reporter: Bennie Schut
Votes: 0
Watchers: 1

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DataNucleus Core

Concurrency Bug: unsynchronized WeakHashMap in

Created: 02/Sep/10 07:00 AM   Updated: 20/Oct/10 09:29 AM   Resolved: 12/Sep/10 10:25 AM
Component/s: None
Affects Version/s: 2.0.3
Fix Version/s: 2.2.0.m2

File Attachments: 1. Text File NUCCORE-559-1.patch (1 kB)

 Description  « Hide
Somewhat similar story as NUCCORE-553. We have hanging threads using 100% cpu.
Is it allowed to have multiple threads calling the JDOClassLoaderResolver? Since it's using the non threadsafe WeakValueMap on the offending code.

"pool-1-thread-41" prio=10 tid=0x00007fb60bc5b800 nid=0x63a2 runnable [0x0000000040f75000]
   java.lang.Thread.State: RUNNABLE
        at java.util.HashMap.get(
        at org.datanucleus.util.ReferenceValueMap.get(
        at org.datanucleus.JDOClassLoaderResolver.classForName(
        at org.datanucleus.JDOClassLoaderResolver.classForName(
        - locked <0x0000000783023778> (a
        at org.datanucleus.sco.SCOUtils.populateMapDelegateWithStoreData(
        at org.datanucleus.sco.backed.Map.loadFromStore(
        at org.datanucleus.sco.backed.Map.load(
        at org.datanucleus.state.JDOStateManagerImpl.loadUnloadedFields(
        at org.datanucleus.jdo.state.Hollow.transitionRetrieve(
        at org.datanucleus.state.AbstractStateManager.retrieve(
        at org.datanucleus.ObjectManagerImpl.retrieveObject(
        at org.datanucleus.jdo.JDOPersistenceManager.jdoRetrieve(
        at org.datanucleus.jdo.JDOPersistenceManager.retrieve(
        - locked <0x0000000782a57bb8> (a org.datanucleus.jdo.JDOPersistenceManager)
        at org.datanucleus.jdo.JDOPersistenceManager.retrieve(
        - locked <0x0000000782a57bb8> (a org.datanucleus.jdo.JDOPersistenceManager)
        at org.apache.hadoop.hive.metastore.ObjectStore.getMTable(

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Bennie Schut added a comment - 03/Sep/10 07:03 AM
Using Collections.synchronizedMap solved this problem for us. Just added a patch as example.

Erik Bengtson added a comment - 12/Sep/10 10:25 AM
thanks for the patch