当使用Http.Put上传大文件时,我会遇到内存不足异常。我正在使用如下代码所示的异步模型。我试图将8K数据块发送到Windows 2008 R2服务器。当我尝试写入超过536,868,864字节的数据块时,异常始终发生。在下面的代码片段中,异常发生在requestStream.Write方法上。
为什么会出现这种情况呢?
注意:较小的文件可以正常上传。如果我写入本地FileStream,则逻辑也能正常工作。客户端计算机上运行VS 2010、.Net 4.0和Win 7 Ultimate操作系统。
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("Http://website/FileServer/filename");
request.Method = WebRequestMethods.Http.Put;
request.SendChunked = true;
request.AllowWriteStreamBuffering = true;
...
request.BeginGetRequestStream( new AsyncCallback(EndGetStreamCallback), state);
...
int chunk = 8192; // other values give same result
....
private static void EndGetStreamCallback(IAsyncResult ar) {
long limit = 0;
long fileLength;
HttpState state = (HttpState)ar.AsyncState;
Stream requestStream = null;
// End the asynchronous call to get the request stream.
try {
requestStream = state.Request.EndGetRequestStream(ar);
// Copy the file contents to the request stream.
FileStream stream = new FileStream(state.FileName, FileMode.Open, FileAccess.Read, FileShare.None, chunk, FileOptions.SequentialScan);
BinaryReader binReader = new BinaryReader(stream);
fileLength = stream.Length;
// Set Position to the beginning of the stream.
binReader.BaseStream.Position = 0;
byte[] fileContents = new byte[chunk];
// Read File from Buffer
while (limit < fileLength)
{
fileContents = binReader.ReadBytes(chunk);
// the next 2 lines attempt to write to network and server
requestStream.Write(fileContents, 0, chunk); // causes Out of memory after 536,868,864 bytes
requestStream.Flush(); // I get same result with or without Flush
limit += chunk;
}
// IMPORTANT: Close the request stream before sending the request.
stream.Close();
requestStream.Close();
}
}
CopyTo()
方法。 - Cameron