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POMulti-threading in ASP.net MVC3 with Code-First EF
 

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  1. POMulti-threading in ASP.net MVC3 with Code-First EF
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    <p>Been looking for a multi-threading solution for my application, but keep getting random <code>NullReferenceException</code> errors when I try, as opposed to when I ran each one consecutively and everything went smoothly.</p> <p>What I'm doing is calculating a journey from one place to another, and then calculating the return journey. The return journey calculation is just to use the same process, only with the departure and destinations switched.</p> <p>Does this sound feasible to do this with multi-threading in an ASP.net MVC3 app with Entity Framework? I've seen a few articles where there seem to be problems with EF, but these sound like they are only an issue when DBContexts are shared on a page, whereas I've used Using statements round all areas where I need to access the database. Anyone have any experience here?</p> <p>The basic relevant code I have so far is this:</p> <pre><code>var outboundJourneyTask = Task.Factory.StartNew(() =&gt; BuildJourney(true)); var returnJourneyTask = Task.Factory.StartNew(() =&gt; BuildJourney(false)); Task.WaitAll(outboundJourneyTask, returnJourneyTask); </code></pre> <p>What I'd hoped was that each task would start afresh, but due to the null reference exceptions, I believe that in the second thread, it is trying to use arrays built in the first, and when it can't find certain elements, it throws errors.</p> <p>Does this sound likely? Anyone know of a better way of doing this?</p> <p>EDIT: I'm trying a different method of threading (see below) but there are really strange things happening with my arrays - looping through them differently and throwing errors</p> <pre><code>Thread t1 = new Thread(ThreadMethod1); t1.Start(); Thread t2 = new Thread(ThreadMethod2); t2.Start(); void ThreadMethod1(object state) { BuildJourney(false); ManualResetEvent mre = (ManualResetEvent)state; mre.Set(); } void ThreadMethod2(object state) { BuildJourney(true); ManualResetEvent mre = (ManualResetEvent)state; mre.Set(); } </code></pre> <p>Thanks</p>
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      1. POMulti-threading in ASP.net MVC3 with Code-First EF
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      1. POMulti-threading in ASP.net MVC3 with Code-First EF
      1. USSean Dunford
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    1. COHow does your `BuildJourney` method looks like?
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      1. USLadislav Mrnka
    2. COIt is big - too big to post here as it contains a lot of other functions and calculations! It takes about 7-10 seconds to process, which is why I want them to run concurrently. It contains a few database calls, several calculations and returns a generic list of viewmodels.
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      1. POMulti-threading in ASP.net MVC3 with Code-First EF
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    3. COBut in such case we can hardly help you if we don't know what resources your call can share.
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      1. POMulti-threading in ASP.net MVC3 with Code-First EF
      1. USLadislav Mrnka
 

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