CODEWITHSUNDEEP
.net.net-4.0streamwriter
Keith
Keith

Reputation: 21244

StreamWriter fails with large amount of data

I'm using StreamWriter to pass a large amount of data (30mb+) via a WebRequest POST. It fails with the error The stream does not support concurrent IO read or write operations. Contrary to the error message, I am not performing concurrent operations -- the app is single threaded and the StreamWriter logic is very straightforward.

string data = "......."; // 30mb+ of text

var webRequest = WebRequest.Create(someUrl);
webRequest.Method = "POST";
webRequest.ContentLength = data.Length;

using (var writer = new StreamWriter(webRequest.GetRequestStream()))
    writer.Write(data);

I suspect the large amount of data is to blame. I've seen references to this error from Team Foundation System users who get this error when uploading large files ([1], [2]), however I haven't seen large data being discussed as the cause outside of TFS discussions.

Am I truly running into some limit with StreamWriter? Is there are more efficient way to stream this data?

Upvotes: 1

Views: 594

Answers (1)

Keith
Keith

Reputation: 21244

The root problem was my POST request was so large that I had exceeded the target server's maxAllowedContentLength setting. The fix was to increase the value of this setting.

I'm not sure why I got a "concurrent IO" error but it only happened when I set webRequest.ContentLength. When I commented that line out I was able to see the WebRequest received a 404 from the server. This eventually led me to discover the issue with maxAllowedContentLength.

Upvotes: 1

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