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

[Artyom B. <art...@ya...>]

1st of all for the iostreams there is a huge difference between debug and release mode additionally all the callback
code of http code depends on optimization.

Also you are right out << in.rdbuf() should be better... probably one of these parts of code I written too fast without thinking...

However I doubt that it is the problem.

How   http::file works when we receive an input data we write it to the memory at first place but after certain threshold it

is written directly to the file instead of memory.  So this part of code has only small use.

Also I suggest when you actually "save" the file use http::file::save_to as it would rather move the file on the disk and not copy it.

If you still have problems with uploading in release more it would be a good idea for me to profile the code. If so I need to know
what version of cppcms you use cppcms 1.0.x or trunk (there were some changes in that part)

 
Artyom Beilis 
-------------- 
CppCMS - C++ Web Framework:   http://cppcms.com/ 
CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/


>________________________________
> From: Cristian Oneț <one...@gm...>
>To: cppcms-users <cpp...@li...> 
>Sent: Monday, October 20, 2014 1:06 PM
>Subject: [Cppcms-users] Slow http:file copy_stream for big files
> 
>
>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
>
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