gnuplot-py-users

[Gnuplot-py-users] Gnuplot.py, FIFOs and threading

[Ken S. <k.w...@qu...>]

Folks

Apologies in advance if there's an FAQ, but I can't find it...  (Feel  
free to point it out to me...)  There also doesn't seem to be a simple  
way to search the Sourceforge archives for this group...

I've been using Gnuplot.py for a while now, and I keep running into  
the same problem.  I'm creating postscript plots, but at the end of my  
script I'd like to convert them into JPEGs using ImageMagick (convert).

The problem is that (presumably because of threading) Gnuplot.py is  
sometimes not completing its work before I attempt to convert the  
plot.  Hence ImageMagic complains about missing postscript files - or  
the postscript files are incomplete when conversion starts.

Is there a way to turn threading/FIFOs OFF?  Or is there a way I can  
use "join" to force my python program to WAIT for the plot to be  
completed before attempting to convert it?

I've tried setting the following after my Gnuplot import:

Gnuplot.GnuplotOpts.prefer_fifo_data = 0
Gnuplot.GnuplotOpts.support_fifo = 0
Gnuplot.GnuplotOpts.prefer_inline_data = 1

but to no avail.  The only thing I'm doing at the moment is checking  
that the postscript file exists - but this is just a fudge and doesn't  
prevent other issues if the file is incomplete.  Below are example  
errors...

Ken



Example errors:

MISSING ps file

convert: unable to open image `/tmp/tempPSPlots/ 
1095652401023547700_lc.ps':  @
error/blob.c/OpenBlob/2584.
convert: missing an image filename
`/psdb/images/ps1ss/lightcurves/1095652401023547700_lc.jpeg' @
error/convert.c/ConvertImageCommand/2949.


INCOMPLETE ps file (presumably that's what causes ghostscript to barf)

Error: /syntaxerror in -file-
Operand stack:
    MLshow
Execution stack:
    %interp_exit   .runexec2   --nostringval--   --nostringval--
    %--nostringval--   2   %stopped_push   --nostringval--   -- 
nostringval--
    %--nostringval--   false   1   %stopped_push   1894   1   3    
%oparray_pop
    %1893   1   3   %oparray_pop   1877   1   3   %oparray_pop    
1771   1   3
    %%oparray_pop   --nostringval--   %errorexec_pop   .runexec2
    %--nostringval--   --nostringval--   --nostringval--   2    
%stopped_push
Dictionary stack:
    --dict:1158/1684(ro)(G)--   --dict:0/20(G)--   --dict:80/200(L)--
--dict:176/256(L)--
Current allocation mode is local
Last OS error: 2
GPL Ghostscript  9.00: Unrecoverable error, exit code 1

Re: [Gnuplot-py-users] Gnuplot.py, FIFOs and threading

[Michael H. <mh...@al...>]

On 08/18/2011 05:31 PM, Ken Smith wrote:
> Apologies in advance if there's an FAQ, but I can't find it...  (Feel  
> free to point it out to me...)

There is a FAQ.txt in the Gnuplot.py distribution.  The first FAQ
question is closely related to your problem.

> The problem is that (presumably because of threading) Gnuplot.py is  
> sometimes not completing its work before I attempt to convert the  
> plot.  Hence ImageMagic complains about missing postscript files - or  
> the postscript files are incomplete when conversion starts.
> 
> Is there a way to turn threading/FIFOs OFF?  Or is there a way I can  
> use "join" to force my python program to WAIT for the plot to be  
> completed before attempting to convert it?

The problem is not so much the multithreading in Gnuplot.py (which
anyway should be turned off if your turn off the use of FIFOs) but
rather the fact that a separate process (the gnuplot program) is doing
the real work.  I believe that if you close() the Gnuplot object
explicitly then it will wait for gnuplot to finish (though of course you
will have to create a new Gnuplot object if you want to do more work
afterwards):

g = Gnuplot.Gnuplot()
# Use g to plot what you want
g.close()
# At this point I think that all of the gnuplot output should be
# done.

Please try this out and tell us if it works.

Michael

-- 
Michael Haggerty
mh...@al...
http://softwareswirl.blogspot.com/

Re: [Gnuplot-py-users] Gnuplot.py, FIFOs and threading

[Ken S. <k.w...@qu...>]

Many thanks Michael

Indeed I just needed to close my Gnuplot() objects.  Not a single  
error (in ~10,000 plots) after I did that.

Cheers,

Ken


On 22 Aug 2011, at 09:22, Michael Haggerty wrote:

> On 08/18/2011 05:31 PM, Ken Smith wrote:
>> Apologies in advance if there's an FAQ, but I can't find it...  (Feel
>> free to point it out to me...)
>
> There is a FAQ.txt in the Gnuplot.py distribution.  The first FAQ
> question is closely related to your problem.
>
>> The problem is that (presumably because of threading) Gnuplot.py is
>> sometimes not completing its work before I attempt to convert the
>> plot.  Hence ImageMagic complains about missing postscript files - or
>> the postscript files are incomplete when conversion starts.
>>
>> Is there a way to turn threading/FIFOs OFF?  Or is there a way I can
>> use "join" to force my python program to WAIT for the plot to be
>> completed before attempting to convert it?
>
> The problem is not so much the multithreading in Gnuplot.py (which
> anyway should be turned off if your turn off the use of FIFOs) but
> rather the fact that a separate process (the gnuplot program) is doing
> the real work.  I believe that if you close() the Gnuplot object
> explicitly then it will wait for gnuplot to finish (though of course  
> you
> will have to create a new Gnuplot object if you want to do more work
> afterwards):
>
> g = Gnuplot.Gnuplot()
> # Use g to plot what you want
> g.close()
> # At this point I think that all of the gnuplot output should be
> # done.
>
> Please try this out and tell us if it works.
>
> Michael
>
> -- 
> Michael Haggerty
> mh...@al...
> http://softwareswirl.blogspot.com/