yang686526

speed when writing large dxf-files (1mb)
speed when writing large dxf-files (1mb)
i have a problem writing large dxf-files.
when writing 10000 line entities (oddbline), a file of around 1mb is created.
the creation of this file takes more then a minut.
there are no problems with reading large files.
in my opinion, it has something to do with io to disk.
i could simulate such a behavior with the example odwriteex.
i adapted the routine dbfiller.cpp on line 460, so 1000 texts were created.
for (i=0; i<1000; i++)
addtextent(pdb, pblock, odgepoint3d(0, dy*3.5, 0) + vec, odgepoint3d(0, dy*3.5, 0) + vec, "bottom right text", textheight, oddb::ktextright,oddb::ktextbottom, layerid, styleid, pgroup);
i think the problem is somewhere in the file odfilebuf.cpp on line 262, routine putbytes
void odbasefilebuf:utbytes(const void* buffer, oduint32 nlen)
{
oda_trace("putbytes(%p, %u)", buffer, nlen);
dword dwbytes = 0;
if( !::writefile(m_hfile, buffer, nlen, &dwbytes, null) || dwbytes != nlen )
{
oda_trace("putbytes() can't write bytes");
throw oderror_fileexception(efilewriteerror, m_sfilename);
}
m_bfilewritten = true;
}
i have the impression that a small number of bytes is written many times.
is there a way to speed this up. (buffer io or something else)
maybe it can also be some other problem.
problem with speed only occurs when writing to mapped network drives
when i write a dxf-file to a local disk, there is absolutely no problem
with the speed. ( it is 50-times faster then when i write to a mapped network drive).
is it possible to get a solution in case of writing to a mapped network drive?
i have noticed that the program dconvertcon.exe has no problems
with mapped network drives. are there some kind of alternative io routines?
filebuf is only a sample implementation. it can be replaced with custom implementation optimized for your platforrm and requirements.
see
sergey slezkin
non win32 version of odwrfilebuf solved the problem for mapped network drive
the problem with speed on mapped networked drive is solved if i
use the non-win32 version of odwrfilebuf in odfilebuf.cpp
thank you.
but note that non-windows (cross-platform) version have no file locking.
sergey slezkin
speed problem reading dxf files on mapped drives
we have noticed a similar mapped drive speed issue with reading dxf files using the 1.13.02 dwgdirect release. we used to use opendwg. the performance problem is not as severe as we had seen with the write of dxf (as this original note also saw) but it is distinctly worse by about 50% from our previous opendwg-based application. we took geert's solution for the write problem and used all of the non-win32 code in odfilebuf.cpp (so it affected both the read and write code) on windows. this solution solved the write problem but not the read problem. does anyone have any other ideas of how this read performance might be affected.
thanks,
barry
dd 1.14 contains new (buffered) implementation of odfilebuf for windows solving this type of problems.
sergey slezkin