On 2012-03-23, at 11:07 AM, Pascal Robert wrote: > > Le 2012-03-23 à 14:05, Chuck Hill a écrit : > >> >> 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… > > Don't you think I already asked? :-/
Do you think we could shame him into it? Hmmm, do we know where he lives? :-P > >> >>> >>> 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 >> >> >> >> >> >> >> >> >> _______________________________________________ >> 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/probert%40macti.ca >> >> This email sent to prob...@macti.ca > -- 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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