convert pdf to png

[Grant Edwards]

On 2007-12-25, Diez B. Roggisch <deets at nospam.web.de> wrote:
> Carl K schrieb:
>> Grant Edwards wrote:
>>> On 2007-12-24, Carl K <carl at personnelware.com> 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.

Unless the file is really huge (or the server is overloaded),
the bytes will probably never even hit a platter.  If you're
using any even remotely modern OS, short-lived tempfiles used
as you desdcribe are basically just memory-buffers with a
filesystem API.

-- 
Grant