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POUsing task parallel library in IEnumerable implementation to achieve speed improvement
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  1. POUsing task parallel library in IEnumerable implementation to achieve speed improvement
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    copied!<p>Following code is simplified version of the code that I am trying to optimize. </p> <pre><code>void Main() { var words = new List&lt;string&gt; {"abcd", "wxyz", "1234"}; foreach (var character in SplitItOut(words)) { Console.WriteLine (character); } } public IEnumerable&lt;char&gt; SplitItOut(IEnumerable&lt;string&gt; words) { foreach (string word in words) { var characters = GetCharacters(word); foreach (char c in characters) { yield return c; } } } char[] GetCharacters(string word) { Thread.Sleep(5000); return word.ToCharArray(); } </code></pre> <p>I cannot change the signature of method SplitItOut.The GetCharacters method is expensive to call but is thread safe. The input to SplitItOut method can contain 100,000+ entries and a single call to GetCharacters() method can take around 200ms. It can also throw exceptions which I can ignore. Order of the results do not matter.</p> <p>In my first attempt I came up with following implementation using TPL which speeds up the things quite a bit, but is blocking till I am done processing all the words.</p> <pre><code>public IEnumerable&lt;char&gt; SplitItOut(IEnumerable&lt;string&gt; words) { Task&lt;char[][]&gt; tasks = Task&lt;char[][]&gt;.Factory.StartNew(() =&gt; { ConcurrentBag&lt;char[]&gt; taskResults = new ConcurrentBag&lt;char[]&gt;(); Parallel.ForEach(words, word =&gt; { taskResults.Add(GetCharacters(word)); }); return taskResults.ToArray(); }); foreach (var wordResult in tasks.Result) { foreach (var c in wordResult) { yield return c; } } } </code></pre> <p>I am looking for any better implementation for method SplitItOut() than this. Lower processing time is my priority here.</p>
 

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