循环中的多线程c＃

Question

我正在使用c＃创建一个工具，它遍历一个大文件目录并提取某些信息。 该目录按语言（LCID）组织，所以我想使用多线程来浏览目录 - 每个语言文件夹一个线程。

我的代码目前扫描少量文件并提取所需的数据而不需要多线程，但是大规模的代码需要很长时间。

我在我的循环中设置了一个获取LCID文件夹的线程，但是出现了以下错误：“'HBscan'没有重载匹配委托System.threading.threadstart”。 从我在网上看到的，然后我把我的方法放在一个类中，所以我可以有参数，现在没有错误，但代码没有正确地迭代文件。 它将文件从扫描中删除。

我想知道是否有人能够看到我的代码在哪里出错，导致它无法正常运行？ 谢谢。

public static void Main(string[] args)
    {
        //change rootDirectory variable to point to directory which you wish to scan through
        string rootDirectory = @"C:\sample";
        DirectoryInfo dir = new DirectoryInfo(rootDirectory);

        //get the LCIDs from the folders
        string[] filePaths = Directory.GetDirectories(rootDirectory);
        for (int i = 0; i < filePaths.Length; i++)
        {
            string LCID = filePaths[i].Split('\\').Last();
            Console.WriteLine(LCID);

            HBScanner scanner = new HBScanner(new DirectoryInfo(filePaths[i]));
            Thread t1 = new Thread(new ThreadStart(scanner.HBscan));              
            t1.Start();             
        } 

        Console.WriteLine("Scanning through files...");

    }
    public class HBScanner
    {
        private DirectoryInfo DirectoryToScan { get; set; }

        public HBScanner(DirectoryInfo startDir)
        {
            DirectoryToScan = startDir;
        }

        public void HBscan()
        {
            HBscan(DirectoryToScan);
        } 

        public static void HBscan(DirectoryInfo directoryToScan)
        {
            //create an array of files using FileInfo object
            FileInfo[] files;
            //get all files for the current directory
            files = directoryToScan.GetFiles("*.*");
            string asset = "";
            string lcid = "";

            //iterate through the directory and get file details
            foreach (FileInfo file in files)
            {
                String name = file.Name;
                DateTime lastModified = file.LastWriteTime;
                String path = file.FullName;

                //first check the file name for asset id using regular expression
                Regex regEx = new Regex(@"([A-Z][A-Z][0-9]{8,10})\.");
                asset = regEx.Match(file.Name).Groups[1].Value.ToString();

                //get LCID from the file path using regular expression
                Regex LCIDregEx = new Regex(@"sample\\(\d{4,5})");
                lcid = LCIDregEx.Match(file.FullName).Groups[1].Value.ToString();

                //if it can't find it from filename, it looks into xml
                if (file.Extension == ".xml" && asset == "")
                {
                    System.Diagnostics.Debug.WriteLine("File is an .XML");
                    System.Diagnostics.Debug.WriteLine("file.FullName is: " + file.FullName);
                    XmlDocument xmlDoc = new XmlDocument();
                    xmlDoc.Load(path);
                    //load XML file in 

                    //check for <assetid> element
                    XmlNode assetIDNode = xmlDoc.GetElementsByTagName("assetid")[0];
                    //check for <Asset> element
                    XmlNode AssetIdNodeWithAttribute = xmlDoc.GetElementsByTagName("Asset")[0];

                    //if there is an <assetid> element
                    if (assetIDNode != null)
                    {
                        asset = assetIDNode.InnerText;
                    }
                    else if (AssetIdNodeWithAttribute != null) //if there is an <asset> element, see if it has an AssetID attribute
                    {
                        //get the attribute 
                        asset = AssetIdNodeWithAttribute.Attributes["AssetId"].Value;

                        if (AssetIdNodeWithAttribute.Attributes != null)
                        {
                            var attributeTest = AssetIdNodeWithAttribute.Attributes["AssetId"];
                            if (attributeTest != null)
                            {
                                asset = attributeTest.Value;
                            }
                        }
                    }
                }

                Item newFile = new Item
                {
                    AssetID = asset,
                    LCID = lcid,
                    LastModifiedDate = lastModified,
                    Path = path,
                    FileName = name
                };

                Console.WriteLine(newFile);

            }

            //get sub-folders for the current directory
            DirectoryInfo[] dirs = directoryToScan.GetDirectories("*.*");
            foreach (DirectoryInfo dir in dirs)
            {
                HBscan(dir);
            }
        }
    }

Answer 1

我没有检查，但我认为这可行。

代码将为每个线程创建一个扫描程序并执行HBscan方法。

public static void Main(string[] args)
        {
            //change rootDirectory variable to point to directory which you wish to scan through
            string rootDirectory = @"C:\sample";
            DirectoryInfo dir = new DirectoryInfo(rootDirectory);

            //get the LCIDs from the folders
            string[] filePaths = Directory.GetDirectories(rootDirectory);
            for (int i = 0; i < filePaths.Length; i++)
            {
                string LCID = filePaths[i].Split('\\').Last();
                Console.WriteLine(LCID);

                Thread t1 = new Thread(() => new HBScanner(new DirectoryInfo(filePaths[i])).HBscan());
                t1.Start();
            }

            Console.WriteLine("Scanning through files...");

        }
        public class HBScanner
        {
            private DirectoryInfo DirectoryToScan { get; set; }

            public HBScanner(DirectoryInfo startDir)
            {
                DirectoryToScan = startDir;
            }

            public void HBscan()
            {
                HBscan(DirectoryToScan);
            }

            public static void HBscan(DirectoryInfo directoryToScan)
            {
                //create an array of files using FileInfo object
                FileInfo[] files;
                //get all files for the current directory
                files = directoryToScan.GetFiles("*.*");
                string asset = "";
                string lcid = "";

                //iterate through the directory and get file details
                foreach (FileInfo file in files)
                {
                    String name = file.Name;
                    DateTime lastModified = file.LastWriteTime;
                    String path = file.FullName;

                    //first check the file name for asset id using regular expression
                    Regex regEx = new Regex(@"([A-Z][A-Z][0-9]{8,10})\.");
                    asset = regEx.Match(file.Name).Groups[1].Value.ToString();

                    //get LCID from the file path using regular expression
                    Regex LCIDregEx = new Regex(@"sample\\(\d{4,5})");
                    lcid = LCIDregEx.Match(file.FullName).Groups[1].Value.ToString();

                    //if it can't find it from filename, it looks into xml
                    if (file.Extension == ".xml" && asset == "")
                    {
                        System.Diagnostics.Debug.WriteLine("File is an .XML");
                        System.Diagnostics.Debug.WriteLine("file.FullName is: " + file.FullName);
                        XmlDocument xmlDoc = new XmlDocument();
                        xmlDoc.Load(path);
                        //load XML file in 

                        //check for <assetid> element
                        XmlNode assetIDNode = xmlDoc.GetElementsByTagName("assetid")[0];
                        //check for <Asset> element
                        XmlNode AssetIdNodeWithAttribute = xmlDoc.GetElementsByTagName("Asset")[0];

                        //if there is an <assetid> element
                        if (assetIDNode != null)
                        {
                            asset = assetIDNode.InnerText;
                        }
                        else if (AssetIdNodeWithAttribute != null) //if there is an <asset> element, see if it has an AssetID attribute
                        {
                            //get the attribute 
                            asset = AssetIdNodeWithAttribute.Attributes["AssetId"].Value;

                            if (AssetIdNodeWithAttribute.Attributes != null)
                            {
                                var attributeTest = AssetIdNodeWithAttribute.Attributes["AssetId"];
                                if (attributeTest != null)
                                {
                                    asset = attributeTest.Value;
                                }
                            }
                        }
                    }

                    Item newFile = new Item
                    {
                        AssetID = asset,
                        LCID = lcid,
                        LastModifiedDate = lastModified,
                        Path = path,
                        FileName = name
                    };

                    Console.WriteLine(newFile);

                }

                //get sub-folders for the current directory
                DirectoryInfo[] dirs = directoryToScan.GetDirectories("*.*");
                foreach (DirectoryInfo dir in dirs)
                {
                    HBscan(dir);
                }
            }
        }

Answer 2

如果您使用的是.NET 4.0，则可以使用TPL并使用Parallel.For / Parallel.ForEach同时处理多个项目相当容易。

几天前我刚接触过它，非常有趣。 它通过在不同内核上使用多个线程来加速您的工作，从而为您提供出色的性能。 由于IO访问过多，因此在您的情况下可能会受到限制。

但它可能值得一试！ （改变你当前的来源是相当容易的，只是检查出来）

Answer 3

怎么样更像这样的东西，

public static void Main(string[] args)
{
    const string rootDirectory = @"C:\sample";

    Directory.EnumerateDirectories(rootDirectory)
        .AsParallel()
        .ForAll(f => HBScannner.HBScan(new DirectoryInfo(f)));
}

毕竟，您只能在循环体内获取LCID以将其写入控制台。 如果你想要将控制权写入你可以做到的，

public static void Main(string[] args)
{
    const string rootDirectory = @"C:\sample";

    Console.WriteLine("Scanning through files...");

    Directory.EnumerateDirectories(rootDirectory)
        .AsParallel()
        .ForAll(f => 
            {
                var lcid = f.Split('\\').Last();
                Console.WriteLine(lcid);

                HBScannner.HBScan(new DirectoryInfo(f));
            });
}

---

请注意，使用EnumerateDirectories应优先于GetDirectories因为它是惰性评估的，因此您的处理可以在找到第一个目录后立即开始。 您不必等待将所有目录加载到列表中。

Answer 4

使用BlockingCollection可以大大改善您的任务http://msdn.microsoft.com/en-us/library/dd267312.aspx 。

整体结构是这样的：你创建一个线程（或在主线程中执行此操作），它将枚举文件并将它们添加到BlockingCollection中。 简单地枚举文件，应该相当快，并且这个线程应该比工作线程更快地完成。

然后，您创建了许多任务（与Environment.ProcessorCount相同的数字将是好的）。 这些任务应该与docs的第一个示例（collection.Take（））类似。 任务应该对一个单独的文件执行检查。

因此，一个线程正在寻找文件名并将它们放入BlockingCollection中，而其他并行线程将检查文件内容。 这样你就可以获得更好的并行性，因为如果你为文件夹创建线程，这可能会造成不均匀的工作分配（你不知道每个文件夹中都有很多文件，对吧？）