[Tutor] same python script now running much slower

Keith Winston keithwins at gmail.com
Tue Dec 31 01:57:46 CET 2013


It seems likely that mentioning what version of Python you're running it on
might help in trouble-shooting... if you can run it on a subsection of your
data, get it down to a workable amount of time (as in, minutes) and then
put timers on the various sections to try to see what's taking so long. My
suspicion, almost wholly free of distortion by facts, is that you are
running it on a different version of Python, either an upgrade or downgrade
was done and something about the script doesn't like that. Is it a terribly
long script?




On Mon, Dec 30, 2013 at 5:37 PM, William Ray Wing <wrw at mac.com> wrote:

> On Dec 30, 2013, at 1:37 PM, "Protas, Meredith" <ProtasM at vision.ucsf.edu>
> wrote:
>
> Hi,
>
> I'm very new to python so I'm sorry about such a basic question.
>
> I am using a python script generated by another person.  I have used this
> script multiple times before and it takes around 24 hours to run.
>  Recently, I have tried to run the script again (the same exact command
> lines) and it is much much slower.  I have tried on two different computers
> with the same result.  I used top to see if there were any suspicious
> functions that were happening but there seems to not be.  I also ran
> another python script I used before and that went at the same speed as
> before so the problem seems unique to the first python script.
>
> Does anyone have any idea why it is so much slower now than it used to be
> (just around a month ago).
>
> Thanks for your help!
>
> Meredith
>
>
> Meredith,  This is just a slight expansion on the note you received from
> Alan.  Is there any chance that the script now is paging itself to death?
>  That is, if you are reading a huge amount of data into a structure in
> memory, and if it no longer fits in available physical memory (either
> because the amount of data to be read has grown or the number of other
> processes that are occupying memory have grown), then that data structure
> may have gone virtual and the OS may be swapping it out to disk.  That
> would dramatically increase the amount of elapsed wall time the program
> takes to run.
>
> If you can tell us more about what the program actually is doing or
> calculating, we might be able to offer more help.
>
> -Bill
>
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-- 
Keith
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