Question

这是我的代码，我对线程安全实现有疑问。我的问题在下面

GetHtmlPageAsync的返回值是object。它是线程安全的吗？我将使用此对象并添加到集合中，最后上传到数据库。
主要方法逻辑如下（实施正在进行中）。我有一组域名，我在集合中有10000个域名列表，我的想法是，我会把它放在队列中并调用GetHtmlPageAsync来获取页面的HTML。基于HTML，我将获得必要的超链接。一旦我获得超链接，我将检查链接中是否有可用的单词。如果链接中有单词，我将调用GetHTMLPageAsync相同的方法来获取该页面的HTML。因此，同一个线程可以调用GetHtmlPageAsync来处理另一个链接。我试图以线程安全的方式重用相同的方法进行多次调用。请帮忙。

@ edit1 。我添加了主要方法。而不是队列。我用过ForEach

public static async Task<int> ProcessDomainAsync(List<string> domains)
    {
        Parallel.ForEach(domains, async (currentDomain) =>
        {
            var domainBody = await GetHtmlPageAsync(currentDomain);
            var language = string.Empty;
            var country = string.Empty;
            var createdOn = DateTime.SpecifyKind(DateTime.Now, DateTimeKind.Local);
            var updatedOn = DateTime.SpecifyKind(DateTime.Now, DateTimeKind.Local);
            var machine = Environment.MachineName;
            var message = "[" + domainBody.ErrorCode + "] - " + domainBody.ErrorMessage;
            var active = false;
            var stage = "End";
            var url = currentDomain;
            if (domainBody.ErrorCode == 0)
            {
                var html = domainBody.Body;
                language = Common.GetLanguageIdentification(html);
                country = Common.GetCountryIdentification(currentDomain);
                message = string.Empty;
                active = true;
                stage = "Stage1";
                var hyperLinks = Common.GetAllAHrefTags(html);
                //Process Hyper Links
            }
            _domainList.Add(new Domain
            {
                Url = url,
                Language = language,
                Country = country,
                MachineName = machine,
                Message = message,
                Active = active,
                Stage = stage,
                CreatedOn = createdOn,
                UpdatedOn = updatedOn
            });
            domainCount++;
        });
        return domainCount;
    }
public class DomainBody
{
    public string Body;
    public string ErrorMessage;
    public int ErrorCode;
}

 public static class DomainProcessing    {

    static async Task<DomainBody> GetHtmlPageAsync(string url)
    {
        #region Initialize Proxy 
        var sessionId = new Random().Next().ToString();
        var proxy = new WebProxy(Constant.ProxyUrl, Constant.ProxyPort);
        var login = Constant.ProxyUserName + "-session-" + sessionId;
        proxy.Credentials = new NetworkCredential(login,Constant.ProxyPassword);
        #endregion

        #region Initialize Variables
        var user_agent = Common.GenerateRandomUserAgent();
        var body = string.Empty;
        var errorCode = 0;
        var errorMessage = string.Empty;
        #endregion

        try
        {
            #region Format URL with Http Protocol

            var domainSB = new StringBuilder();
            domainSB.Append("http://");
            domainSB.Append(url);

            #endregion

            #region Process Domain

            var request = (HttpWebRequest) WebRequest.Create(new Uri(url));
            request.Proxy = proxy;
            request.UserAgent = user_agent;
            request.Timeout = Constant.TimeOut;

            using (var response = await request.GetResponseAsync().ConfigureAwait(true))
            using (var content = new MemoryStream())
            using (var responseStream = response.GetResponseStream())
            {
                await responseStream.CopyToAsync(content);
                var bodyArray = content.ToArray();
                body = Encoding.UTF8.GetString(bodyArray, 0, bodyArray.Length);
            }

            errorCode = 0;
            errorMessage = string.Empty;

            #endregion 
        }
        catch (HttpRequestException ex)
        {
            body = string.Empty;
            errorCode = ex.InnerException.HResult;
            errorMessage = ex.InnerException.Message;
        }
        catch (Exception ex)
        {
            body = string.Empty;
            errorCode = ex.HResult;
            errorMessage = ex.Message;
        }

        var domainBody = new DomainBody
        {
            Body = body,
            ErrorCode = errorCode,
            ErrorMessage = errorMessage
        };

        return domainBody;
    }
}enter code here

Answer 1

一般来说，局部变量应该是线程安全的（仅仅是因为他们根本不知道有另一个线程和其他线程无法访问它们）。

应该查看多个线程可以访问的任何内容。例如_domainList。确保Add方法是线程安全的，因为您可能并行调用它。

.NET Core 2.0以下代码线程是安全的

1 个答案: