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Common Khadka
Common Khadka

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PLINQ Extension Methods in C#

#csharp #programming

Parallel LINQ (PLINQ) is an extension of LINQ that enables parallel processing of queries to improve performance by utilizing multiple cores of a processor. Below is a list of PLINQ extension methods along with code snippets demonstrating their usage.

1. AsParallel

Converts an IEnumerable to a parallel query, enabling parallel execution.

var numbers = Enumerable.Range(1, 10); var parallelQuery = numbers.AsParallel().Where(n => n % 2 == 0); foreach (var num in parallelQuery) { Console.WriteLine(num); }
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2. WithDegreeOfParallelism

Limits the number of processor cores used for the query execution.

var numbers = Enumerable.Range(1, 20); var parallelQuery = numbers.AsParallel() .WithDegreeOfParallelism(2) // Limits to 2 cores .Where(n => n % 2 == 0); foreach (var num in parallelQuery) { Console.WriteLine(num); }
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3. ParallelEnumerable.Range

Generates a range of numbers in parallel.

var parallelRange = ParallelEnumerable.Range(1, 10); parallelRange.ForAll(Console.WriteLine);
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4. ParallelEnumerable.Repeat

Generates a sequence where a specified value is repeated multiple times in parallel.

var repeatedValues = ParallelEnumerable.Repeat("Hello", 5); repeatedValues.ForAll(Console.WriteLine);
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5. ParallelEnumerable.Empty

Returns an empty parallel sequence.

var emptySequence = ParallelEnumerable.Empty<int>(); Console.WriteLine("Count: " + emptySequence.Count());
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6. AsSequential

Forces a PLINQ query to process sequentially instead of in parallel.

var numbers = Enumerable.Range(1, 10).AsParallel(); var sequentialQuery = numbers.AsSequential().Where(n => n % 2 == 0); foreach (var num in sequentialQuery) { Console.WriteLine(num); }
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7. AsOrdered

Preserves the ordering of the original sequence in a PLINQ query.

var numbers = Enumerable.Range(1, 10).AsParallel().AsOrdered(); foreach (var num in numbers) { Console.WriteLine(num); }
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8. AsUnordered

Removes ordering constraints for better parallel performance.

var numbers = Enumerable.Range(1, 10).AsParallel().AsUnordered(); numbers.ForAll(Console.WriteLine);
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9. WithCancellation

Enables cancellation of a PLINQ query using a CancellationToken.

var cts = new CancellationTokenSource(); var numbers = Enumerable.Range(1, 100).AsParallel().WithCancellation(cts.Token); Task.Run(() => cts.Cancel()); try { foreach (var num in numbers) { Console.WriteLine(num); } } catch (OperationCanceledException) { Console.WriteLine("Query was canceled."); }
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10. WithMergeOptions

Specifies how results should be merged after parallel execution.

var numbers = Enumerable.Range(1, 10).AsParallel() .WithMergeOptions(ParallelMergeOptions.NotBuffered); numbers.ForAll(Console.WriteLine);
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11. WithExecutionMode

Forces a query to run in parallel or sequential mode.

var numbers = Enumerable.Range(1, 10).AsParallel() .WithExecutionMode(ParallelExecutionMode.ForceParallelism); numbers.ForAll(Console.WriteLine);
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12. ForAll

Executes a parallel query and applies an action to each element.

var numbers = Enumerable.Range(1, 10).AsParallel(); numbers.ForAll(Console.WriteLine);
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Conclusion

PLINQ provides powerful methods to enable efficient parallel processing in C#. Understanding these methods can help improve performance in applications that handle large data processing tasks.

References

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