A concurrent second call is made on an object before the first is completed

Both calls are being made on the very same proxy. The initially call is the modelling run (which is time consuming and the contact is not one method - hence the client thread waits until the organization procedure is completed) and whilst this is going on any type of calls to the organization on the exact same proxy initially work-related however then lock (the number of effective calls before locking is variable).

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If you setup on executing an operation object manually, rather of adding it to a queue, you can design your operation to execute in a conexisting or non-concurrent manner. Operation objects are non-conexisting by default. In a non-conexisting procedure, the operation’s job is percreated synchronously—that is, the procedure object does not develop a sepaprice thcheck out on which to run the task. Therefore, once you speak to the start approach of a non-conpresent procedure directly from your code, the operation executes instantly in the present thread.


By the moment the begin method of such an object returns regulate to the caller, the task itself is finish.In comparison to a non-concurrent operation, which runs synchronously, a conpresent procedure runs asynchronously. In other words, as soon as you contact the start approach of a concurrent procedure, that approach can rerotate before the matching job is completed. This could happen because the operation object produced a new thread to execute the job or bereason the procedure dubbed an asynchronous feature. It does not actually matter if the procedure is recurring as soon as manage returns to the caller, only that it could be continuous. When Apple offers conpresent vs non-conpresent in this conmessage, they expect "does the begin strategy rerotate immediately".

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For instance, take the following to "start" implementations:. Concurrent OperationWhen this begin approach retransforms, the operation won"t be complete yet. Since NSOperation can not depend on this technique returning as a signal that the project is complete, you now need to handle informing the operation"s queue if it"s executing, finished, etc.

By sfinishing KVO willChangeValueForKey: and also didChangeValueForKey: notifications for the "isExecuting" and "isFinished" keycourses. This indicates you must do a bit even more work-related in order to obtain the procedure up, running and managing its state, yet you have actually a lot more regulate. Click to expand.you stated listed below that you override begin and it makes it a conexisting procedure, so it runs parrellel to the primary thread. But your second "non-concurrent" instance (which suggests it doesnt not run in parallel to the primary thread???) likewise has actually start overridden. That really confused me.or did i obtain it entirely wrong, regardmuch less whether its conpresent or non-conpresent the procedure runs in a sepeprice thread?my various other question is: is it true that if you use NSOperationqueue through NSOperation i wouldn"t need to issue around all that??

Click to expand also.First of all, I made a mistake in the code, the non-concurrent operation should override - NSOperation primary, not - NSOperation begin. In this case, do not issue around whether you are on the main thread or not; if you are using an NSOperationQueue it will automatically handle all the bits of setting up a sepaprice queue and also dispatching the operations you add.

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The conpresent vs non-concurrent relates exclusively to just how you are managing the lifecycle of the NSOperation. A non-conexisting procedure has the adhering to lifecycle:. myOperationQueue addOperation:myNonconcurrentOperation. NSOperation start. MyNonconcurrentOperation main. procedure completed!In a non-conexisting operation, the necessary thing to realize is that the begin (and the major you implement) strategy block till the operation is completed, however long that takes.

It does not matter what threview the operation is on, the necessary component is that as soon as your main method retransforms, the operation is done and rerelocated from the queue; NSOperation handles the lifecycle tracking, establishing isExecuting, isFiniburned, etc.A conexisting procedure has the complying with lifecycle:. myOperationQueue addOperation:myNonconcurrentOperation. MyNonconcurrentOperation begin // Sets up and also starts the operation. Doing points for my operation. I.e.: waiting for NSURLConnection delegate callbacks, and so on finished the operation so fire off the isExecuting and isFinimelted KVO notifications.

procedure completed!In a concurrent procedure, you (or, the developer) handles tracking the lifecycle of an procedure and also notifying the NSOperation of what state it need to be in. This implies that the NSOperation it not taken into consideration finish when the start method returns; it is only complete as soon as isFinimelted is set to "YES" and the proper KVO notifications are sent.

Click to expand also.To a huge degree, it really relies on what form of operations you are trying to wrap. Take scaling and rotating a UIImage; You.have the right to. implement it as a concurrent operation, however it would certainly be a lot much easier to implement as a non-conexisting NSOperation (it"s a synchronous, processor intensive operation).

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However before, if you have to use something prefer NSXMLParser, a non-conpresent procedure would be messy and also tough compared to a conpresent implementation because of the asynchronous delegation API.