On 2012-03-23, at 10:56 AM, John Huss wrote: > Cayenne supports this kind of concurrency and will utilize multiple > connections to the database without requiring a duplicate stack like EOF > does. So for concurrency it is a much better choice than EOF. And it's > easy to get started if you're familiar with EOF already. It can be used > inside a WO app with no problems.
That sounds like a great WOWODC presentation just waiting to happen... > > John > > On Fri, Mar 23, 2012 at 10:58 AM, Ramsey Gurley <ramseygur...@gmail.com> > wrote: > My main goal is to better understand EOF conceptually :-) I was playing with > the ERXOSCPool just for kicks and found a leak. I wondered why an entirely > new OSC was even needed to make a second connection to the db. Seems like > overkill. So I fugetuboutit. > > Later, I'm rereading through the old docs and find that little gem about > opening new database channels. It seems that at least conceptually, creating > new channels would be the proper way to handle multiple connections to the > database. > > But it doesn't work. After finding the object store lock… I wonder if it ever > worked? The fact that it was documented makes me think that maybe once upon > a time, it worked. However, this wouldn't be the first time the docs were > totally wrong. The fact that it suggests making every session in the app a > listener for that notification only reinforces my suspicions that the docs > were just wrong. > > Because of the lock, that notification is only ever fired once. So it's > possible to create multiple connections, but only one of them will ever be > used. The docs also suggest that an EODatabase may have multiple > EODatabaseContexts. But then this will have the same problem with the object > store lock and may even exhibit the same problem that results in leaks in the > OSCPool. > > I'm coming to the conclusion that the best way to distribute load across > multiple channels would be to simply have multiple instances of an app. > Knowing that would definitely have an influence on any sort of bulk > processing operations I might design in the future. > > I also wonder if this information can be used to implement more effective > load balancing. No reason to direct users to an instance if one user on that > instance has EOF tied up fetching a large blob out of the database for > instance. I'll have to look for the location of the load balancer in WO > sometime. I'd like to see how it works. > > Anyway, thanks for all the input everyone :-) I think I understand the point > of the object store lock now. > > Ramsey > > On Mar 22, 2012, at 7:53 PM, Chuck Hill wrote: > > > OK, so... my first question has to be "what is your goal? What are you > > trying to accomplish?" This is NOT going to make EOF multi-threaded. > > > > > > Chuck > > > > > > On 2012-03-22, at 7:34 PM, Ramsey Gurley wrote: > > > >> Hi all, > >> > >> I'm looking at trying to open multiple database channels in a single > >> instance of a WO app. No reason, just wondering if it can be done. I know > >> there's ERXObjectStoreCoordinator pool, but this conceptually seems like > >> the wrong way to do it. Maybe I want 4 open connections for one database, > >> but only one on another… whatever. So I have a look at > >> > >> https://developer.apple.com/legacy/mac/library/documentation/WebObjects/Enterprise_Objects/Connecting/Connecting.html#//apple_ref/doc/uid/TP30001011-CH210-TPXREF145 > >> > >> and this seems to be the answer to my question. Well, until I try it. It > >> turns out that inside of objectsWithFetchSpec on EOEditingContext, the > >> objectstore is locked before a fetch takes place. As a result, no other > >> fetch can proceed until the object store is unlocked. The answer seemed > >> suspicious in the fact that it's being done on the Session anyway... > >> > >> So, I guess my question boils down to… is it even possible? Is this the > >> 'single EOF lock' that Chuck Hill and Ravi Mendis were referring to in a > >> previous list message? > >> > >> Thanks, > >> > >> Ramsey > >> > >> > >> _______________________________________________ > >> Do not post admin requests to the list. They will be ignored. > >> Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) > >> Help/Unsubscribe/Update your Subscription: > >> https://lists.apple.com/mailman/options/webobjects-dev/chill%40global-village.net > >> > >> This email sent to ch...@global-village.net > > > > -- > > Chuck Hill Senior Consultant / VP Development > > > > Practical WebObjects - for developers who want to increase their overall > > knowledge of WebObjects or who are trying to solve specific problems. > > http://www.global-village.net/gvc/practical_webobjects > > > > > > > > > > > > > > > > > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/webobjects-dev/johnthuss%40gmail.com > > This email sent to johnth...@gmail.com > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/webobjects-dev/chill%40global-village.net > > This email sent to ch...@global-village.net -- Chuck Hill Senior Consultant / VP Development Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems. http://www.global-village.net/gvc/practical_webobjects
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