plinq

It doesn't seem to do squat for the following test program. Is this because I'm testing with a small list? static void Main(string[] args) { List<int> list = 0.UpTo(4); Test(list.AsParallel()); Test(list); } private static void Test(IEnumerable<int> input) { var timer = new Stopwatch(); timer.Start(); var size = input.Count(); if (input.Where(IsOdd).Count() != size / 2) throw new Exception("Failed to count the odds"); timer.Stop(); Console.WriteLine("Tested " + size + " numbers in " + timer.Elapsed.TotalSeconds + " seconds"); } private static bool IsOdd(int n) { Thread.Sleep(1000); return n%2

PLINQ was added in the .NET 4.0 Framework as an extension to LINQ. What is it? What problems does it solve? When is it appropriate and when not? This is Parallel LINQ. It's a way to run LINQ queries in parallel on multi-core/multi-processor systems, in order to (hopefully) speed them up. There is a good article on this in MSDN Magazine . For current details and plans, I recommend reading articles on the Parallel Programming with .NET Team Blog . They are the team implementing the parallel extensions, including PLINQ. PLINQ is LINQ executed in Parallel, that is, using as much processing power

I have a 2-dimensional byte array that looks something like this: 0 0 0 0 1 1 1 1 1 0 0 0 1 1 1 1 0 1 0 1 Each value in the array can only be 0 or 1. The above simplified example shows 4 rows with each row having 5 columns. I am trying to figure out how to use LINQ to return the index to the row that has the largest number of 1s set, which in the above example should return 1. The following non LINQ C# code solves the problem: static int GetMaxIndex(byte[,] TwoDArray) { // This method finds the row with the greatest number of 1s set. // int NumRows = TwoDArray.GetLength(0); int NumCols =

Say I have an IO-bound task. I'm using WithDegreeOfParallelism = 10 and WithExecution = ForceParallelism mode, but still the query only uses two threads. Why? I understand PLINQ will usually choose a degree of parallelism equal to my core count, but why does it ignore my specific request for higher parallelism? static void Main(string[] args) { TestParallel(0.UpTo(8)); } private static void TestParallel(IEnumerable<int> input) { var timer = new Stopwatch(); timer.Start(); var size = input.Count(); if (input.AsParallel(). WithDegreeOfParallelism(10). WithExecutionMode(ParallelExecutionMode

I came across this situation where the following plinq statement inside static constructor gets deadlocked: static void Main(string[] args) { new Blah(); } class Blah { static Blah() { Enumerable.Range(1, 10000) .AsParallel() .Select(n => n * 3) .ToList(); } } It happens only when a constructor is static. Can someone explain this to me please. Is it TPL bug? Compiler? Me? It is generally dangerous to call threading code from a static constructor. In order to ensure that the static constructor executes only once, the CLR executes the static constructor under a lock. If the thread running the

What is the difference between these two? What is the best way to compare ? It is always better plinq ? When we use plinq ? Linq is a collection of technologies that work together to solve a similar family of problems - in all of them you have a source of data (xml file or files, database contents, collection of objects in memory) and you want to retrieve some or all of this data and act on it in some way. Linq works on the commonality of that set of problems such that: var brithdays = from user in users where user.dob.Date == DateTime.Today && user.ReceiveMails select new{user.Firstname, user

Amazingly, using PLINQ did not yield benefits on a small test case I created; in fact, it was even worse than usual LINQ. Here's the test code: int repeatedCount = 10000000; private void button1_Click(object sender, EventArgs e) { var currTime = DateTime.Now; var strList = Enumerable.Repeat(10, repeatedCount); var result = strList.AsParallel().Sum(); var currTime2 = DateTime.Now; textBox1.Text = (currTime2.Ticks-currTime.Ticks).ToString(); } private void button2_Click(object sender, EventArgs e) { var currTime = DateTime.Now; var strList = Enumerable.Repeat(10, repeatedCount); var result =