Consuming less memory when writing a file?

[W. Jordan]

Hello,

I am using Response.WriteFile (filename) to write a file that on
the server to my web client.

I discover that the while a client request a big file,
for example, a 14m-bytes one, the memory usage of the
w3wp.exe increases the same amount of 14m.

That might be horrible if I allow the users to download a 32m
or greater file. Is it possible to conserve a little memory while
writing files to the client.

 

[Daniel Fisher\(lennybacon\)]

Tr something like

 

[Daniel Fisher\(lennybacon\)]

Try something like the following (set this.m_bufferSize to the size you want
to allocate in memory):

context.Response.Buffer = false;
FileStream _fileStream = null;
byte[] _buffer = new byte[this.m_bufferSize];
long _byteCount;
try
{
_fileStream = File.OpenRead(_filePath);
while ((_byteCount = _fileStream.Read(_buffer, 0, _buffer.Length)) > 0)
{
if(context.Response.IsClientConnected)
{
context.Response.OutputStream.Write(_buffer, 0, _buffer.Length);
context.Response.Flush();
}
else
{
return;
}
}
}
catch(Exception _ex)
{
throw _ex;
}
finally
{
_fileStream.Close();
context.Response.End();
}

 

[Daniel Fisher\(lennybacon\)]

Try something like the following (set this.m_bufferSize to the size you want
to allocate in memory):

context.Response.Buffer = false;
FileStream _fileStream = null;
byte[] _buffer = new byte[this.m_bufferSize];
long _byteCount;
try
{
_fileStream = File.OpenRead(_filePath);
while ((_byteCount = _fileStream.Read(_buffer, 0, _buffer.Length)) > 0)
{
if(context.Response.IsClientConnected)
{
context.Response.OutputStream.Write(_buffer, 0, _buffer.Length);
context.Response.Flush();
}
else
{
return;
}
}
}
catch(Exception _ex)
{
throw _ex;
}
finally
{
_fileStream.Close();
context.Response.End();
}

 

[John Timney \( MVP \)]

Someone has done a very good job of explaining the cause of the problem, and
how to work out a solution here:

http://www.devx.com/dotnet/Article/22533

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director

 

[W. Jordan]

Hello,

I changed the code slightly to the following and monitored
the memory usage with the task manager.
I am sad to find that during the downloading, the memory
usage goes up still. The sample file used for download testing
was 14mb, and the memory consumption delta went up more than
twice of the file size.

Response.Clear ();
Response.Buffer = false;
Response.AppendHeader("Content-Type", "octet-stream");
Response.AppendHeader("Content-Disposition","attachment");
Response.Flush ();
int bufferSize = 8192;
byte[] buffer = new byte[bufferSize];
long byteCount;
using (FileStream fs = File.OpenRead (AppPath.MapPath (fileName)))
{
while ((byteCount = fs.Read (buffer, 0, buffer.Length)) > 0)
{
if (Response.IsClientConnected)
{
Response.OutputStream.Write (buffer, 0, buffer.Length);
Response.Flush ();
}
else
{
return ;
}
}
}


--

Best Regards,
W. Jordan

Try something like the following (set this.m_bufferSize to the size you
want to allocate in memory):

context.Response.Buffer = false;
FileStream _fileStream = null;
byte[] _buffer = new byte[this.m_bufferSize];
long _byteCount;
try
{
_fileStream = File.OpenRead(_filePath);
while ((_byteCount = _fileStream.Read(_buffer, 0, _buffer.Length)) > 0)
{
if(context.Response.IsClientConnected)
{
context.Response.OutputStream.Write(_buffer, 0, _buffer.Length);
context.Response.Flush();
}
else
{
return;
}
}
}
catch(Exception _ex)
{
throw _ex;
}
finally
{
_fileStream.Close();
context.Response.End();
}


--
Daniel Fisher(lennybacon)
http://www.lennybacon.com

Hello,

I am using Response.WriteFile (filename) to write a file that on
the server to my web client.

I discover that the while a client request a big file,
for example, a 14m-bytes one, the memory usage of the
w3wp.exe increases the same amount of 14m.

That might be horrible if I allow the users to download a 32m
or greater file. Is it possible to conserve a little memory while
writing files to the client.

 

[W. Jordan]

Hello,

I am downloading the code and will examine it.
Thank you for providing this information!


--

Best Regards,
W. Jordan

 

[W. Jordan]

Hi Danial,

I tried to change Response.Flush to Response.OutputStream.Flush.

The performance appears to be a little better, however, the
memory usage problem is still there.
Perhaps, there're still a huge buffer inside the FileStream.
Thus, the while loop will fill it up and thus the memory consumption
goes up accordingly.

--

Best Regards,
W. Jordan

Try something like the following (set this.m_bufferSize to the size you
want to allocate in memory):

context.Response.Buffer = false;
FileStream _fileStream = null;
byte[] _buffer = new byte[this.m_bufferSize];
long _byteCount;
try
{
_fileStream = File.OpenRead(_filePath);
while ((_byteCount = _fileStream.Read(_buffer, 0, _buffer.Length)) > 0)
{
if(context.Response.IsClientConnected)
{
context.Response.OutputStream.Write(_buffer, 0, _buffer.Length);
context.Response.Flush();
}
else
{
return;
}
}
}
catch(Exception _ex)
{
throw _ex;
}
finally
{
_fileStream.Close();
context.Response.End();
}


--
Daniel Fisher(lennybacon)
http://www.lennybacon.com

Hello,

I am using Response.WriteFile (filename) to write a file that on
the server to my web client.

I discover that the while a client request a big file,
for example, a 14m-bytes one, the memory usage of the
w3wp.exe increases the same amount of 14m.

That might be horrible if I allow the users to download a 32m
or greater file. Is it possible to conserve a little memory while
writing files to the client.