GNU bug report logs - #30644
Cuirass runs out of build users

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Message #50 received at 30644 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Danny Milosavljevic <dannym <at> scratchpost.org>
Cc: Andreas Enge <andreas <at> enge.fr>, 30644 <at> debbugs.gnu.org
Subject: Re: bug#30644: Cuirass runs out of build users
Date: Sun, 25 Mar 2018 14:40:20 +0200

Hi Danny,

Danny Milosavljevic <dannym <at> scratchpost.org> skribis:

> I've checked it some more.  The shared cache uses unlock_notify, and the actual
> database uses sqlite3_busy_handler (sqlite3_busy_timeout) when BUSY is returned.
>
> The 5 in
>
> ice-9/eval.scm:619:8: Throw to key `sqlite-error' with args `(#f 5 "database is locked")'.  
>                                                                  ^^
>
> means SQLITE_BUSY, so that's the actual database.
>
> So the easiest way to work around it would be to call
>
>   sqlite3_busy_timeout(db, 10); // ms
>
> which would automatically repeatedly retry on busy until 10 ms have accumulated,
> and only then give up.

Indeed, that’s actually what nix/libstore does.

> There's also sqlite3_busy_handler which can be used to install a busy handler,
> and of course in the future we could also handle SQLITE_BUSY ourselves and yield.
>
> See also https://notabug.org/civodul/guile-sqlite3/pulls/4 for the former.

Awesome.

I’ve merged these guile-sqlite3 bits and added a “PRAGMA busy_timeout”
in Cuirass (the pragma allows us to set the timeout even when using an
older guile-sqlite3.)  I’ve updated the ‘cuirass’ package and will test
soonish on berlin.

Thank you!

Ludo’.

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