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Q about locked ec
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Q about locked ec

  • Subject: Q about locked ec
  • From: Philippe Rabier <email@hidden>
  • Date: Wed, 17 Feb 2010 20:34:27 +0100
Hi all,

I get an issue with a multi threaded application. To be easier to understand, my description is simpler than the reality but that's enough to see what's going on I guess.

I'm using:
WO 5.4.3
Snow Leopard/ java 6
Wonder (not the very last but not old)
I put the following properties:
er.extensions.ERXEC.traceOpenLocks=true
er.extensions.ERXEC.markOpenLocks=true

There 2 threads (not worker threads handled by WO) created by a frameworkPrincipal (in the wonder sense) with a classical run loop (while (true)....).

BigObject A running in thread A has an editingContext A (ecA) that fetches, for example, customers from entity Customer

BigObject B running in thread B has an editingContext B (ecB) that fetches objects, for example invoices from entity Invoice. Invoice has a to one relationship with Customer

BigObject A passes to BigObject B a list of customers. Suppose there is only one customer in the list.

Object B periodically fetches invoices, customer by customer, so it constructs a qualifier like invoice.customer.eq(aCustomer), then a fetchspec, ... Of course, there is some code like:

ecB.lock();
try
invoices = ecB.objectsWithFetchSpecification(fetchSpecification);
catch
finally
ecB.unlock();

The log tells me that when ecB.objectsWithFetchSpecification is executed, ecA is locked. And it's locked forever. I wasn't sure to have to use a localInstance of customer because I use it only to create a qualifier. But I did the test and it's worth.

If I execute something like that before the construction of the qualifier:
 myCustomers = EOUtilities.localInstanceOfObject(ecB, customers);

ecA and ecB are locked automatically and never unlocked.

I found a solution, that's to lock/unlock both editingContexts but I'm unsatisfied because I don't understand why EOUtilities.localInstance locks ecA and ecB and doesn't unlock them. Naturally I would find the good way to use it.

Any idea what's going on? 

The stack trace when ecA is locked by BigObjectB:

Outstanding at @Thread[Thread-4,5,main]
java.lang.Exception: Locked
at er.extensions.eof.ERXEC.traceLock(ERXEC.java:532)
at er.extensions.eof.ERXEC.lock(ERXEC.java:502)
at er.extensions.eof.ERXEC.autoLock(ERXEC.java:627)
at er.extensions.eof.ERXEC.globalIDForObject(ERXEC.java:844)
at com.webobjects.eoaccess.EODatabaseContext._globalIDForObject(EODatabaseContext.java:4644)
at com.webobjects.eoaccess.EODatabaseContext.databaseOperationForObject(EODatabaseContext.java:4767)
at com.webobjects.eoaccess.EODatabaseContext.valuesForKeys(EODatabaseContext.java:6535)
at com.webobjects.eocontrol.EOObjectStoreCoordinator.valuesForKeys(EOObjectStoreCoordinator.java:326)
at com.webobjects.eoaccess.EOQualifierSQLGeneration$_KeyValueQualifierSupport.schemaBasedQualifierWithRootEntity(EOQualifierSQLGeneration.java:439)
at er.extensions.ERXExtensions$KeyValueQualifierSQLGenerationSupport.schemaBasedQualifierWithRootEntity(ERXExtensions.java:333)
at com.webobjects.eoaccess.EOQualifierSQLGeneration$Support._schemaBasedQualifierWithRootEntity(EOQualifierSQLGeneration.java:179)
at com.webobjects.eoaccess.EOQualifierSQLGeneration$_AndQualifierSupport.schemaBasedQualifierWithRootEntity(EOQualifierSQLGeneration.java:530)
at com.webobjects.eoaccess.EOQualifierSQLGeneration$Support._schemaBasedQualifierWithRootEntity(EOQualifierSQLGeneration.java:179)
at com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecification(EODatabaseChannel.java:227)
at com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(EODatabaseContext.java:3055)
at com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3195)
at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488)
at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069)
at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1211)
at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4444)
at fr.sophiacom.ynp.push.BigObjectB.fetchesInvoice(BigObjectB.java:238)
at fr.sophiacom.BigObjectB._run(BigObjectB.java:110)
at er.extensions.concurrency.ERXRunnable.run(ERXRunnable.java:23)
at java.lang.Thread.run(Thread.java:637)

Philippe

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