When handling large file transfers in ASP.NET what

问题:

My ASP.NET application allows users to upload and download large files. Both procedures involve reading and writing filestreams. What should I do to ensure the application doesn't hang or crash when it handles a large file? Should the file operations be handled on a worker thread for example?

回答1:

Make sure you properly buffer the files so that they don't take inordinate amounts of memory in the system.

e.g. excerpt from a download application, inside the while loop that reads the file:

// Read the data in buffer.
length = iStream.Read(buffer, 0, bufferSize);

// Write the data to the current output stream.
Response.OutputStream.Write(buffer, 0, length);

Where bufferSize is something reasonable, e.g. 100000 bytes, the trade-off is that it will be slower for smaller buffer sizes.

http://support.microsoft.com/kb/812406

Edit: Also be sure that IIS is set to take a large enough request length (IIS7) and timeout.

回答2:

Unless this is the primary purpose of your site consider partitioning these operations to a separate application, e.g. a sub-application or sub-domain. Besides reducing risk this would also simplify scaling out as your user base grows.