Diez B. Roggisch wrote: > Carl K schrieb: >> Grant Edwards wrote: >>> On 2007-12-24, Carl K <[EMAIL PROTECTED]> wrote: >>> >>>>> If it is a multi page pdf Imagemagick will do: >>>>> >>>>> convert file.pdf page-%03d.png >>>> I need python code to do this. It is going to be run on a >>>> someone else's shared host web server, security and >>>> performance is an issue. So I would rather not run stuff via >>>> popen. >>> >>> Use subprocess. >>> >>> Trying to eliminate popen because of the overhead when running >>> ghostscript to render PDF (I assume convert uses gs?) is about >>> like trimming an elephants toenails to save weight. >>> >> >> maybe, but I wouldn't be so sure. >> >> currently the pdf is created in a python StringIO buffer and returned >> to the browser; so it never becomes a file. using convert means I >> have to first save it as a file, convert from file to file, read the >> file, delete the 2 files. so 6 file operations where before there were >> none. That may be more of a load than the ghostscript part. > > So what? I'm not sure about current HD speeds, but a couple of years ago > these were about 30MByte/s - and should be faster today. Which equals > 240MBit/s, much more than your user's internet connection. and this is > raw IO speed, not counting disk caches.
server is doing a ton of SQL queries (yes, moving to a 2nd box would be nice. might happen mid 2008) so adding HD is an issue. not sure how much, but enough to try to avoid it. > > In other words: given the overall latency of a network connection, your > file operations shouldn't shave off more than a split-second. those split seconds can add up. The server is aleady overloaded, so adding more is a big no no. > So if you > _can_ go the subprocess-road, do it. It's the easiest way. And withou > further knowledge of the GS-library (that you lack, as do I) - how do > you know that it works "in memory", and doesn't actually expect a > file-name or pointer? I am willing to take that chance. much better than the 6 hits I know would happen using I have a feeling if I have to create a file, we will go with plan B: send the client a pdf and let the user deal with it. Not as nice and slick, but won't bog the server. Carl K -- http://mail.python.org/mailman/listinfo/python-list
