From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: [BUG?] gc and impatience
Date: Fri, 2 Aug 2013 21:44:11 -0700
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Cc: Ramkumar Ramachandra <artagnon@gmail.com>,
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To: Duy Nguyen <pclouds@gmail.com>
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On Fri, Aug 2, 2013 at 8:53 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> Good point. I think that is because gc does not check if gc is already
> running. Adding such a check should not be too hard. I think gc could
> save its pid in $GIT_DIR/auto-gc.pid. The next auto-gc checks this, if
> the pid is valid, skip auto-gc.

Defining "valid" is a tricky business, though, as pid can and will
wrap around, and the directory could be shared on multiple machines. A
pid written by a process on one machine has no relation to any pid on
another machine.