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Re: GNU Parallel Bug Reports tail follow with parallel
From: |
Ole Tange |
Subject: |
Re: GNU Parallel Bug Reports tail follow with parallel |
Date: |
Thu, 7 Aug 2014 10:13:02 +0200 |
On Wed, Aug 6, 2014 at 11:00 AM, Jaap Kroes <address@hidden> wrote:
> Hello,
>
> I have a problem using parallel with 'tail -f'. For example:
>
> seq 10 > test ; tail -f test | parallel -j2 'echo {}'
>
> This will not read to the end of the file, but to EOF-n lines, where n is
> the number of procs.
>
> Is this a bug in GNU-parallel?
>From the man-page:
There is a a small issue when using GNU parallel as queue
system/batch manager: You have to submit JobSlot number of jobs
before they will start, and after that you can submit one at a time,
and job will start immediately if free slots are available. Output
from the running or completed jobs are held back and will only be
printed when JobSlots more jobs has been started (unless you use
--ungroup or -u, in which case the output from the jobs are printed
immediately). E.g. if you have 10 jobslots then the output from the
first completed job will only be printed when job 11 has started, and
the output of second completed job will only be printed when job 12
has started.
So the job is run; it is just the output that is delayed.
/Ole