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EOEditingContext Lock/Unlock best practice?
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EOEditingContext Lock/Unlock best practice?

  • Subject: EOEditingContext Lock/Unlock best practice?
  • From: shravan kumar <email@hidden>
  • Date: Tue, 7 Apr 2009 13:35:33 -0700 (PDT)
Hello Group,

Can somebody with good experience in dealing with EOEditingContext lock/ unlock concept please advise me the following best practice in locking/ unlocking EOEditingContext in various possible scenarios:

1) I have created an instance of EOEditingContext using EREXC.newEditingContext() in my WOComponent constructor. All/ most of the dynamic elements in the WOComponent have object binding i.e., Employee Name = employee.name, Employee Dept Name = employee.dept.name

I have locked and unlocked ec in the action methods properly as advised in the WO articles. Thanks for the documentation.

However, as the dynamic elements have object binding, EOF is throwing below error while submitting the form and almost similar error while loading the form:


[2009-04-08 01:47:56 IST] <WorkerThread6> *** EOEditingContext: access with no lock: objectWillChange()!

[2009-04-08 01:47:56 IST] <WorkerThread6> java.lang.Exception: This is not a real exception, just a stack trace of the location of the missing lock:

at com.webobjects.eocontrol.EOEditingContext._EOAssertSafeMultiThreadedAccess(EOEditingContext.java:5173)

at com.webobjects.eocontrol.EOEditingContext.objectWillChange(EOEditingContext.java:2814)

at er.extensions.ERXEC.objectWillChange(ERXEC.java:733)

at com.webobjects.eocontrol.EOObserverCenter.notifyObserversObjectWillChange(EOObserverCenter.java:433)

at com.webobjects.eocontrol.EOCustomObject.willChange(EOCustomObject.java:271)

at com.webobjects.eocontrol._EOMutableKnownKeyDictionary$Initializer$_GenericRecordBinding.setValueInObject(_EOMutableKnownKeyDictionary.java:527)

at com.webobjects.eocontrol.EOCustomObject.takeStoredValueForKey(EOCustomObject.java:1778)

at com.org.model._Employee.setName(_MemoryBooksPrice.java:53)

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:585)

at com.webobjects.foundation.NSKeyValueCoding$ValueAccessor$1.setMethodValue(NSKeyValueCoding.java:688)

at com.webobjects.foundation.NSKeyValueCoding$_MethodBinding.setValueInObject(NSKeyValueCoding.java:1175)

at com.webobjects.eocontrol.EOCustomObject.takeValueForKey(EOCustomObject.java:1601)

at com.webobjects.foundation.NSKeyValueCoding$Utility.takeValueForKey(NSKeyValueCoding.java:519)

at com.webobjects.foundation.NSValidation$DefaultImplementation.validateTakeValueForKeyPath(NSValidation.java:733)

at com.webobjects.eocontrol.EOCustomObject.validateTakeValueForKeyPath(EOCustomObject.java:1363)

at com.webobjects.foundation.NSValidation$Utility.validateTakeValueForKeyPath(NSValidation.java:551)

at com.webobjects.foundation.NSValidation$DefaultImplementation.validateTakeValueForKeyPath(NSValidation.java:741)

at com.webobjects.appserver.WOComponent.validateTakeValueForKeyPath(WOComponent.java:1273)

at com.webobjects.appserver._private.WOKeyValueAssociation.setValue(WOKeyValueAssociation.java:71)

at com.webobjects.appserver._private.WOTextField.takeValuesFromRequest(WOTextField.java:81)

at com.webobjects.appserver._private.WODynamicGroup.takeChildrenValuesFromRequest(WODynamicGroup.java:81)

at com.webobjects.appserver._private.WODynamicGroup.takeValuesFromRequest(WODynamicGroup.java:89)

at com.webobjects.appserver._private.WOForm.takeValuesFromRequest(WOForm.java:70)

at com.webobjects.appserver._private.WODynamicGroup.takeChildrenValuesFromRequest(WODynamicGroup.java:81)

at com.webobjects.appserver._private.WODynamicGroup.takeValuesFromRequest(WODynamicGroup.java:89)

at com.webobjects.appserver.WOComponent.takeValuesFromRequest(WOComponent.java:914)

at com.webobjects.appserver.WOSession.takeValuesFromRequest(WOSession.java:1139)

at com.webobjects.appserver.WOApplication.takeValuesFromRequest(WOApplication.java:1350)


I have heard that we can lock/ unlock EOEditingContext in the WOComponent awake() and sleep() methods. But I have also read that this is not completely true, as sleep() method of a component may not be called sometimes i.e., when a different component is returned in response or when there is an exception in component lifecycle, it seems sleep() method is not invoked.

"Question: Given these caveats and any other, please advise me *BEST PRACTICE* (that overcomes dangerous locking/ unlocking issues like: deadlock and ...) in locking/ unlocking EOEditingContext object in various scenarios like, the ones described above."


Thanks for the early response.

Thank You,
Shravan Kumar. M

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