Re: GNU Parallel Bug Reports inefficiency of --pipe -L

[Ole Tange]

On Sun, Sep 9, 2012 at 6:39 AM, Martin Frith <address@hidden> wrote:
> Hello:
>
> The NEWS file mentions that '-L n --pipe' is useful for fastq.  I tried
> this, and it works, but extremely slowly.  On the other hand, using '-N'
> instead of '-L' works and is much faster.
>
> I'm using GNU parallel 20120822.  Here is how to reproduce the problem:
>
> seq 100000 > fake.fastq
>
> # This works and is fast:
> time parallel --pipe -N10000 cat < fake.fastq > out1
>
> # These work but are extremely slow:
> time parallel --pipe -L10000 cat < fake.fastq > out2a
> time parallel --pipe -L4 cat < fake.fastq > out2b
> time parallel --pipe -L4 --block 1M cat < fake.fastq > out2c

Confirmed. See http://savannah.gnu.org/bugs/?37325

/Ole