[Cppcms-users] Slow http:file copy_stream for big files

[Cristian O. <one...@gm...>]

Hi,

I'm using a simplified version (no widgets::file only request::files)
of the uploader [1] to implement an upload service. What I observed is
that uploading large files takes a lot of CPU and takes way more than
a similar nodejs service [2] (1 min vs 1 s for the same file - 300
MB). I have to admit that this was cppcms compiled in debug against a
release nodejs but the difference is too great.

Intrigued by this finding I've took a glimpse at how the file is saved
to the temporary location using the input stream and found [3].
Reading from the input stream in 1024 byte chunks then writing that to
the output does not seem such a great idea and could explain the high
CPU usage and the overall slowness.

Shouldn't this perform better?

out << in.rdbuf();

I promise I'll get back with the results of running a release build.

Regards,
Cristian

[1] http://cppcms.com/cppcms_ref/latest/ex_uploads____uploader__cpp.html
[2] https://github.com/felixge/node-formidable
[3] http://sourceforge.net/p/cppcms/code/HEAD/tree/framework/trunk/src/http_file.cpp#l78