Question

我正在调用下面的方法，它使iOS内存从40MB上升到160MB，它不会再次下降。再次执行它会杀死应用程序，因为它是OOM。我已经尝试了一切，但我看不出有问题。它正在调用一个返回大量数据（5MB到10MB）字符串的Web服务。我只想阅读它并将其存储在一个文件中。

public void GetDataStreamed ( int iID, string sFilename )
{
    string sUrl = "somewebservice.com/somemethod" ;

    WebRequest request = WebRequest.Create ( sUrl );
    // Set the Method property of the request to POST.
    request.Method = "POST";
    // Create POST data and convert it to a byte array.
    string postData = "sSessionID=" + this.SessionID + "&iID=" + iID.ToString (  ) + "&iDepth=-1&iRootID=-1&aObjectTypes=2&aObjectTypes=3&aObjectTypes=4&aObjectTypes=6";
    byte[] byteArray = Encoding.UTF8.GetBytes ( postData );
    // Set the ContentType property of the WebRequest.
    request.ContentType = "application/x-www-form-urlencoded";
    // Set the ContentLength property of the WebRequest.
    request.ContentLength = byteArray.Length;
    request.Timeout = 60000;

    // Get the request stream.
    using(Stream dataStream = request.GetRequestStream (  ))
    {
        // Write the data to the request stream.
        dataStream.Write ( byteArray, 0, byteArray.Length );
        // Close the Stream object.
        dataStream.Close (  );
    }

    // Read response and stream into a file.
    HttpWebResponse oResponse = ( HttpWebResponse ) request.GetResponse (  );
    Stream oResponseStream = oResponse.GetResponseStream (  );
    using ( StreamWriter oFileWriter = new StreamWriter ( sFilename ) )
    {
        using ( StreamReader oReader = new StreamReader ( oResponseStream ) )
        {

            while ( !oReader.EndOfStream )
            {
                string s = oReader.ReadLine (  );
                oFileWriter.WriteLine ( System.Web.HttpUtility.HtmlDecode ( s ) );
                oFileWriter.Flush();
            }
            oReader.Close (  );
        }
        oFileWriter.Close();
    }

}

Answer 1

我只是偶然发现了这篇文章，你可能已经想到了这一点。在您提供的代码片段中，您不会处置应使用块的以下对象：

WebRequest
HttpWebResponse
Stream

一旦你离开了这个方法，它们使用的内存仍然被保留，不会被垃圾收集。

作为旁注，Dispose（）会关闭连接，这是using语句的语法糖的原因之一，因此您不必记得调用close。如果除了另一个using语句之外没有其他正文，你也可以使用没有大括号的语句进行堆叠。这是一个快速而肮脏的重构示例，您提供了缺少的using语句。这应该可以纠正您遇到的内存泄漏。

public void GetDataStreamed(int iID, string sFilename)
{
    string sUrl = "somewebservice.com/somemethod" ;

    using (WebRequest request = WebRequest.Create (sUrl))
    {
        // Set the Method property of the request to POST.
        request.Method = "POST";
        // Create POST data and convert it to a byte array.
        string postData = "sSessionID=" + this.SessionID + "&iID=" + iID.ToString() + "&iDepth=-1&iRootID=-1&aObjectTypes=2&aObjectTypes=3&aObjectTypes=4&aObjectTypes=6";
        byte[] byteArray = Encoding.UTF8.GetBytes(postData);
        // Set the ContentType property of the WebRequest.
        request.ContentType = "application/x-www-form-urlencoded";
        // Set the ContentLength property of the WebRequest.
        request.ContentLength = byteArray.Length;
        request.Timeout = 60000;

        // Get the request stream.
        using(Stream dataStream = request.GetRequestStream())
        {
            // Write the data to the request stream.
            dataStream.Write(byteArray, 0, byteArray.Length);
            // Close the Stream object.
            dataStream.Close();
        }

        // Read response and stream into a file.
        using(HttpWebResponse oResponse = (HttpWebResponse) request.GetResponse ( ))
        using(Stream oResponseStream = oResponse.GetResponseStream ())
        using(StreamWriter oFileWriter = new StreamWriter (sFilename))
        using(StreamReader oReader = new StreamReader (oResponseStream))
        {
            while(!oReader.EndOfStream)
            {
                string s = oReader.ReadLine();
                oFileWriter.WriteLine (System.Web.HttpUtility.HtmlDecode(s));
                oFileWriter.Flush();
            }
        }
    }
}

Answer 2

如果只需要将其下载到文件中，请使用WebClient（）。DownloadFile（）代替。

Answer 3

您是否使用显式.Close（）来确保关闭读者和作者？我认为Using {}为你做了那个？

是什么让这段代码占用iOS上的所有内存？

3 个答案: