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From: Dima Kogan <dima@secretsauce.net>
To: zsh-workers@zsh.org
Subject: zargs parallelization support blows up with |&
Date: Mon, 27 Jul 2015 02:36:36 -0700
Message-ID: <87lhe23psr.fsf@secretsauce.net>
MIME-Version: 1.0
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Hi. I can use this to invoke a perl script 10 times, 2 processes at a
time:

 zargs -P2 -i -l1 `seq 10` -- perl -e 'sleep 20' {}

This works ok. However, when I do the same thing, but filter stdout and
stderr for some output, then ALL the processes are invoked at the same
time, not just 2 at a time like I asked:

 zargs -P2 -i -l1 `seq 10` -- perl -e 'sleep 20' {} |& grep x

I don't know if this is a bug or an expected consequence of some
internal implementation details, but this is a really nasty failure
mode.

Thanks for looking.
dima