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POWhy this difference between foreach vs Parallel.ForEach?
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  1. POWhy this difference between foreach vs Parallel.ForEach?
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    copied!<p>Can anyone explain to me in simple langauage why I get a file about 65 k when using foreach and more then 3 GB when using Parallel.ForEach?</p> <p>The code for the foreach:</p> <pre><code>// start node xml document var logItems = new XElement("log", new XAttribute("start", DateTime.Now.ToString("yyyy-MM-ddTHH:mm:ss"))); var products = new ProductLogic().SelectProducts(); var productGroupLogic = new ProductGroupLogic(); var productOptionLogic = new ProductOptionLogic(); // loop through all products foreach (var product in products) { // is in a specific group var id = Convert.ToInt32(product["ProductID"]); var isInGroup = productGroupLogic.GetProductGroups(new int[] { id }.ToList(), groupId).Count &gt; 0; // get product stock per option var productSizes = productOptionLogic.GetProductStockByProductId(id).ToList(); // any stock available var stock = productSizes.Sum(ps =&gt; ps.Stock); var hasStock = stock &gt; 0; // get webpage for this product var productUrl = string.Format(url, id); var htmlPage = Html.Page.GetWebPage(productUrl); // check if there is anything to log var addToLog = false; XElement sizeElements = null; // if has no stock or in group if (!hasStock || isInGroupNew) { // page shows =&gt; not ok =&gt; LOG! if (!htmlPage.NotFound) addToLog = true; } // if page is ok if (htmlPage.IsOk) { sizeElements = GetSizeElements(htmlPage.Html, productSizes); addToLog = sizeElements != null; } if (addToLog) logItems.Add(CreateElement(productUrl, htmlPage, stock, isInGroup, sizeElements)); } // save var xDocument = new XDocument(new XDeclaration("1.0", "utf-8", "yes"), new XElement("log", logItems)); xDocument.Save(fileName); </code></pre> <p>Use of the parallel code is a minor change, just replaced the foreach with Parallel.ForEach:</p> <pre><code>// loop through all products Parallel.ForEach(products, product =&gt; { ... code ... }; </code></pre> <p>The methods GetSizeElements and CreateElements are both static.</p> <p><strong>update1</strong> I made the methods GetSizeElements and CreateElements threadsafe with a lock, also doesn't help.</p> <p><strong>update2</strong> I get answer to solve the problem. That's nice and fine. But I would like to get some more insigths on why this codes creates a file that is so much bigger then the foreach solutions. I am trying get some more sense in how the code is working when using threads. That way I get more insight and can I learn to avoid the pitfalls.</p>
 

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