parallel-extensions

I'm using LINQ to compare two DataSets with each other to create new rows and update existing. I've noticed that the complete comparison lasts ~1,5 hours and only one of the two cores is busy(Task-Manager is 50-52% CPU Usage). I must admit that I'm completely new to parallel LINQ, but I assume that it could increase performance significantly. So my question is, how and what should I parallelize? These are the original queries(reduced to the essentials): 'check for new data Dim srcUnique = From row In src.Email_Total Select Ticket_ID = row.ticket_id, Interaction = row.interaction, ModifiedAt =

While I was using Parallel.ForEach in my program, I found that some threads never seemed to finish. In fact, it kept spawning new threads over and over, a behaviour that I wasn't expecting and definitely don't want. I was able to reproduce this behaviour with the following code which, just like my 'real' program, both uses processor and memory a lot (.NET 4.0 code): public class Node { public Node Previous { get; private set; } public Node(Node previous) { Previous = previous; } } public class Program { public static void Main(string[] args) { DateTime startMoment = DateTime.Now; int

So for example: ConcurrentDictionary<string,Payload> itemCache = GetItems(); foreach(KeyValuePair<string,Payload> kvPair in itemCache) { if(TestItemExpiry(kvPair.Value)) { // Remove expired item. Payload removedItem; itemCache.TryRemove(kvPair.Key, out removedItem); } } Obviously with an ordinary Dictionary this will throw an exception because removing items changes the dictionary's internal state during the life of the enumeration. It's my understanding that this is not the case for a ConcurrentDictionary as the provided IEnumerable handles internal state changing. Am I understanding this

I am using the below code var processed = new List<Guid>(); Parallel.ForEach(items, item => { processed.Add(SomeProcessingFunc(item)); }); Is the above code thread safe? Is there a chance of processed list getting corrupted? Or should i use a lock before adding? var processed = new List<Guid>(); Parallel.ForEach(items, item => { lock(items.SyncRoot) processed.Add(SomeProcessingFunc(item)); }); thanks. No! It is not safe at all, because processed.Add is not. You can do following: items.AsParallel().Select(item => SomeProcessingFunc(item)).ToList(); Keep in mind that Parallel.ForEach was created

I have a question concerning parallel for loops. I have the following code: public static void MultiplicateArray(double[] array, double factor) { for (int i = 0; i < array.Length; i++) { array[i] = array[i] * factor; } } public static void MultiplicateArray(double[] arrayToChange, double[] multiplication) { for (int i = 0; i < arrayToChange.Length; i++) { arrayToChange[i] = arrayToChange[i] * multiplication[i]; } } public static void MultiplicateArray(double[] arrayToChange, double[,] multiArray, int dimension) { for (int i = 0; i < arrayToChange.Length; i++) { arrayToChange[i] = arrayToChange

In one of my projects that's kinda an aggregator, I parse feeds, podcasts and so from the web. If I use sequential approach, given that a large number of resources, it takes quite a time to process all of them (because of network issues and similar stuff); foreach(feed in feeds) { read_from_web(feed) parse(feed) } So I want to implement concurrency and couldn't decide if I should basically use ThreadPools to process with worker threads or just rely on TPL to get it sorted. ThreadPools for sure will handle the job for me with worker threads and I'll get what I expect (and in multi-core CPU