On 4 December 2013 15:08, William Stein <[email protected]> wrote:
> On Wed, Dec 4, 2013 at 7:00 AM, John Cremona <[email protected]> wrote:
>> I have been having great success with the @parallel decorator, but
>> sometimes I cannot work out why it is not doing everything that I
>> expect.  Perhaps someone can help?
>>
>> The setup is simple.  I have a function process_one(L, N1, N2) which
>> takes a string L as input (plus a couple of other parameters) and
>> returns a string as output.  This gets the parallel decorator.  It is
>> managed by a controlling function process_all() which opens an input
>> file inf and an output file, uses inf.readlines() to get an iterator
>> over all lines of the input, calls process_one() on each and writes
>> the result to the screen and the output file.  I do not care that the
>> output files's lines are in random order since I can easily sort them
>> afterwards.
>>
>> The code for this function looks very like this (I only changed the name)
>>
>> def process_all(infile, N1, N2, outfile=None):
>>     inf = open(infile)
>>     if outfile:
>>         outf = open(outfile,'w')
>>     output_lines = rank1_line([(L,N1,N2) for L in inf.readlines()])
>>     for input_line, output_line in output_lines:
>>             print output_line
>>             if outfile:
>>                 outf.write(output_line)
>>                 outf.write("\n")
>>                 outf.flush()
>>     inf.close()
>>     if outfile:
>>         outf.close()
>>
>> When I run this on a file with 10000 lines it works fine (say with
>> @parallel(20)) but when I run it on a file with two or a few lines it
>> tends to process the first lines but not  all (and never returns), or
>> on a file with 10 lines then most will run but not the others and the
>> function never returns.
>>
>> In case it is relevant, the inner function process_one() uses system()
>> to call gp with some input, whose output is piped to a file which is
>> then read.  I don't use Sage's own pari/gp since the function I need
>> is only in pari-2.6.0.
>>
>
> There's nothing obviously (to me) wrong with your code.  Is there any way
> you could provide a complete working example to illustrate the problem, i.e.,
> something somebody could run unchanged?
>

Yes, easily, iff you have a version of gp with the ellheegner() function!

Thanks,

John

> William
>
>> John
>>
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>
>
> --
> William Stein
> Professor of Mathematics
> University of Washington
> http://wstein.org
>
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