[ncl-talk] The slow down when addfile is used in do loop

[Yuqiang Zhang]

Maybe try to delete the variables using “delete” command after each loop. 

 

Regards,

Yuqiang

 

From: ncl-talk-bounces at ucar.edu [mailto:ncl-talk-bounces at ucar.edu] On Behalf Of Ruping Mo
Sent: Friday, September 12, 2014 4:31 PM
To: ncl-talk
Subject: [ncl-talk] The slow down when addfile is used in do loop

 

Hi NCLers,

 

I have an archive of large grib files. Each grib file contains a month of multiple daily global variables. I use the following script to extract a small part of one variable. The script, which uses addfile in a large loop, runs very fast for the first few months, then begins to slow down substantially. I let it run for a few years, then terminate the job (Ctrl-Z) and re-run the same script. Surprisingly, the new job runs very fast to the month when the previous job was terminated. I wonder why it behaves this way, and what I can do to avoid the slow down problem.

 

Have a nice day!

 

Ruping

 

The script:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

begin

 nday = 12784     ; number of days from Jan 1979 to Dec 2013

 temp = new((/nday, 9, 9/), float)

;;;;

 t0 = 0

 do yr = 1979, 2013

   syr = tostring(yr)

   do mo = 1, 12

    smo = tostring(mo)

    print(syr + "-" + smo)

    fname = syr + "/" + syr + "-" + smo + ".grib"

    dat = addfile(fname, "r")

    mday = getfilevardimsizes(dat, "initial_time0") - 1

    i1 = i0 + mday

    temp(i0:i1, :, :) = (/ dat->2T_GDS0_SFC(:, 80:88, 146:154) /)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 2T_GDS0_SFC(mday, 241, 480)

    i0 = i1 + 1

   end do

 end do

end

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

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