FTP上传-内存泄漏问题

Question

我正在开发一个使用 FTP 协议上传和下载大文件的个人项目。除了我最近注意到的内存泄漏之外，它工作正常。我不知道到底是什么问题。这可能是内存泄漏或糟糕的编程。此应用程序使用的内存量在上传时每秒都在增加。代码如下：

    Action action;
    int bufferSize = 16384;
    EventLogger elog = new EventLogger();
    string error = "";
    string filename = "";

    public Uploader(Action action)
    {
        this.action = action;
        filename = action.directory.Substring(action.directory.LastIndexOf('\\') + 1,
            action.directory.Length - action.directory.LastIndexOf('\\') - 1);
    }

    public bool startUpload()
    {   
        try
        {
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://*******");
            request.Method = WebRequestMethods.Ftp.ListDirectory;
            request.Credentials = new NetworkCredential("***", "***");

            FtpWebResponse response = (FtpWebResponse)request.GetResponse();

            Stream responseStream = response.GetResponseStream();
            StreamReader reader = new StreamReader(responseStream);
            List<string> files = new List<string>();
            string[] filesArr = reader.ReadToEnd().Split('\n');
            reader.Close();
            response.Close();
            foreach (string file in filesArr)
                files.Add(file.Replace("\r", ""));
            if (files.IndexOf(filename) != -1)
            {
                request = (FtpWebRequest)WebRequest.Create("ftp://***/"+filename);
                request.Method = WebRequestMethods.Ftp.DeleteFile;
                request.Credentials = new NetworkCredential("***", "***");
                response = (FtpWebResponse)request.GetResponse();
                reader.Close();
                response.Close();
                if (response.StatusCode != FtpStatusCode.FileActionOK)
                {
                    return false;
                }
            }

            request = (FtpWebRequest)WebRequest.Create("ftp://***/"+filename);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            request.KeepAlive = false;
            request.UseBinary = true;

            FileStream stream = File.OpenRead(action.directory);
            byte[] buffer = new byte[bufferSize];
            Stream reqStream = request.GetRequestStream();

            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = "update DIRECT_UPLOAD set COMPLETED = @com, PROGRESS = @prog, SPEED = @speed where ID = @id";
            cmd.Parameters.AddWithValue("@id", action.id);
            cmd.Parameters.AddWithValue("@com", 0);
            cmd.Parameters.AddWithValue("@prog", 0);
            cmd.Parameters.AddWithValue("@speed", 0);


            long i = 0;
            int readed = 0;
            int total = 0;
            int speed = 0;
            DateTime last = DateTime.Now;
            int lastTotal = 0;
            while ((readed = stream.Read(buffer, 0, bufferSize)) > 0)
            {
                reqStream.Write(buffer, 0, readed);
                total += readed;
                if (i % 100 == 0)
                {
                    cmd.Parameters["@com"].Value = total;
                    cmd.Parameters["@prog"].Value = (int)(((double)total / action.size) * 100);
                    int tot = 0;
                    tot = total - lastTotal;
                    int time = Convert.ToInt32((DateTime.Now - last).TotalMilliseconds);
                    speed = (int)(((double)1000.0 / time) * tot);
                    cmd.Parameters["@speed"].Value = speed;
                    if ((error = SqlProcess.sqlNonQuery(cmd)) != "")
                        throw new Exception(error);
                    last = DateTime.Now;
                    lastTotal = total;
                }

                Application.DoEvents();
                i++;
            }

            cmd.Parameters["@com"].Value = total;
            cmd.Parameters["@prog"].Value = 100;
            cmd.Parameters["@speed"].Value = 0;
            if ((error = SqlProcess.sqlNonQuery(cmd)) != "")
                throw new Exception(error);

            reqStream.Close();
            stream.Close();
        }
        catch (Exception ex)
        {
            elog.write(ex);
            return false;
        }
        return true;
    }

谢谢。

Answer 1

检查您在此处使用的所有对象以确保它们不需要是Dispose-d（即它们是否实现了IDisposable？）。否则，每次执行此代码时，您都会遇到与每个对象关联的非托管资源泄漏。

您可以使用using 整齐地确保以异常安全的方式为此类对象调用Dispose()。

示例 - 代替：

SqlCommand cmd = new SqlCommand();

使用它来包装使用cmd的代码

using (SqlCommand cmd = new SqlCommand())
{
}

请注意，如果您的 EventLogger 类是通过（例如）File 或 EventLog 包装非托管资源的自定义类，则它可能还需要实现 IDisposable。

您可以在 MSDN 文档中查看您在此处和其他地方使用的其他内置类。