Re: currently saving for so it cannot prepare to save for

Hi, Chad,

On Jan 19, 2006, at 9:12 AM, Chad Pilkington wrote:

> When you use rawRowsForSQL does it use the object store coordinator.

Yes.

> I am using it to fetch some results from queries?  Is it possible  
> that when I am using rawRowForSQL and someone else tries to save  
> that this error occurs?

That's the most likely scenario for triggering this exception.

You can download a copy of the CountFetcher class that Alex Cone,  
Lenny Marx and I collaborated on at:

      http://wocode.com/cgi-bin/WebObjects/WOCode.woa/2/wa/ 
ShareCodeItem?itemId=429

It shows code that plays with the lower levels of the EOStack and how  
the EOObjectStoreCoordinator should be locked.

Regards,
Jerry



> ----- Original Message -----
> From: Jerry W. Walker
> To: Chad Pilkington
> Cc: [email protected]
> Sent: Thursday, January 19, 2006 8:53 AM
> Subject: Re: currently saving for so it cannot prepare to save for
>
> Hi, Chad,
>
> This looks like a failure to lock the EOObjectStoreCoordinator.  
> Typically, this is done by default in the standard use of the  
> default editing context. The following is from the  
> EOObjectStoreCoordinator JavaDoc documentation for the lock method:
>
> ========================
> This method is used to protect access to the receiver from  
> concurrent operations by multiple threads. EOEditingContexts will  
> indirectly lock their EOObjectStoreCoordinators when necessary.  
> Locking an EOObjectStoreCoordinator will cause the coordinator to  
> lock each registered EOCooperatingObjectStore managed by that  
> coordinator. Applications which make direct use of an  
> EOObjectStoreCoordinator should lock and unlock it as appropriate.  
> Do not confuse this with any methods which work with the database  
> locking mechanism.
> ========================
>
> If you reformat your error message as follows it looks more like a  
> stack trace:
>
> ========================
> IllegalStateException: prepareForSaveWithCoordinator:  
> EODatabaseContext@e9e799 is currently saving for  
> EOEditingContext@aa0933 so it cannot prepare to save for  
> EOEditingContext@c73be3.
>
> EOObjectStoreCoordinator@3d2b3 has sources (EODatabaseContext@e9e799)
> at EODatabaseContext.prepareForSaveWithCoordinator 
> (EODatabaseContext.java:5763)
> at EOObjectStoreCoordinator.saveChangesInEditingContext 
> (EOObjectStoreCoordinator.java:405)
> at EOEditingContext.saveChanges(EOEditingContext.java:3128)
> at Main.actLoginAdmin(Main.java:328)
> at sun.reflect.GeneratedMethodAccessor174.invoke(Unknown Source)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke 
> (DelegatingMethodAccessorImpl.java:25)
> at reflect.Method.invoke(Method.java:324)
> at KeyValueCodingProtectedAccessor.methodValue 
> (KeyValueCodingProtectedAccessor.java:54)
> at NSKeyValueCoding$_MethodBinding.valueInObject 
> (NSKeyValueCoding.java:1160)
> at NSKeyValueCoding$DefaultImplementation.valueForKey 
> (NSKeyValueCoding.java:1268)
> at WOComponent.valueForKey(WOComponent.java:1544)
> ========================
>
> The error seems to be occurring at Main.actLoginAdmin(Main.java: 
> 328). You might start with that statement to see if any code is  
> directly accessing the EOObjectStoreCoordinator directly without  
> locking.
>
> You also mentioned that you are only using the Session's default  
> editing context and sometimes a child thereof. The child editing  
> contexts should be explicitly locked. Check also to be sure that  
> the code is not creating a peer editing context by leaving out the  
> reference to the default editing context in the constructor message.
>
> HTH.
>
> Regards,
> Jerry
>
> On Jan 18, 2006, at 9:38 PM, Chad Pilkington wrote:
>
>> I have an applicaton where I am getting this error a lot:
>> java.lang.IllegalStateException: prepareForSaveWithCoordinator:  
>> com.webobjects.eoaccess.EODatabaseContext@e9e799 is currently  
>> saving for com.webobjects.eocontrol.EOEditingContext@aa0933 so it  
>> cannot prepare to save for  
>> com.webobjects.eocontrol.EOEditingContext@c73be3.  
>> com.webobjects.eocontrol.EOObjectStoreCoordinator@3d2b3 has  
>> sources (com.webobjects.eoaccess.EODatabaseContext@e9e799) at  
>> com.webobjects.eoaccess.EODatabaseContext.prepareForSaveWithCoordinat 
>> or(EODatabaseContext.java:5763) at  
>> com.webobjects.eocontrol.EOObjectStoreCoordinator.saveChangesInEditin 
>> gContext(EOObjectStoreCoordinator.java:405) at  
>> com.webobjects.eocontrol.EOEditingContext.saveChanges 
>> (EOEditingContext.java:3128) at Main.actLoginAdmin(Main.java:328)  
>> at sun.reflect.GeneratedMethodAccessor174.invoke(Unknown Source)  
>> at sun.reflect.DelegatingMethodAccessorImpl.invoke 
>> (DelegatingMethodAccessorImpl.java:25) at  
>> java.lang.reflect.Method.invoke(Method.java:324) at  
>> KeyValueCodingProtectedAccessor.methodValue 
>> (KeyValueCodingProtectedAccessor.java:54) at  
>> com.webobjects.foundation.NSKeyValueCoding 
>> $_MethodBinding.valueInObject(NSKeyValueCoding.java:1160) at  
>> com.webobjects.foundation.NSKeyValueCoding 
>> $DefaultImplementation.valueForKey(NSKeyValueCoding.java:1268) at  
>> com.webobjects.appserver.WOComponent.valueForKey(WOComponent.java: 
>> 1544)
>>
>> I am having difficulty discovering exactly how this particuar  
>> error is possible using only one EOModel and one Instance of an  
>> application.  I  have never seen this error before in any of my  
>> other applications.  The only real difference that I can see is  
>> that this application has a mySql v 4.0.18 backend where our other  
>> applications have OpenBase backend. As far as I can tell this  
>> error is occuring at a far higher level then the actual database  
>> level.  The application is running on OSX 10.2.8 via monitor.  It  
>> was built in WebObjects 5.2 and is using the  
>> org.gjt.mm.mysql.Driver v 3.0.8.  The application is not using any  
>> special Editing Contexts.  just the session().defaultEditingContext 
>> () and the occational child of that contect new EOEditngContext 
>> (session().defaultEditingContext()).  Does anyone have any idea  
>> what the problem is?
>> _______________________________________________
>> WebObjects-dev mailing list
>> [email protected]
>> http://www.omnigroup.com/mailman/listinfo/webobjects-dev
>
>
> --
> __ Jerry W. Walker,
>    WebObjects Developer/Instructor for High Performance Industrial  
> Strength Internet Enabled Systems
>
>     [email protected]
>     203 278-4085        office
>
>
>
>
>
> _______________________________________________
> WebObjects-dev mailing list
> [email protected]
> http://www.omnigroup.com/mailman/listinfo/webobjects-dev
>


--
__ Jerry W. Walker,
    WebObjects Developer/Instructor for High Performance Industrial  
Strength Internet Enabled Systems

     [email protected]
     203 278-4085        office

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