From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#30644: Cuirass runs out of build users
Date: Sun, 25 Mar 2018 14:40:20 +0200
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References: <20180228090714.GA1845@jurong> <20180302140833.GB3213@macbook41>
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To: Danny Milosavljevic <dannym@scratchpost.org>
Cc: 30644@debbugs.gnu.org

Hi Danny,

Danny Milosavljevic <dannym@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 re=
turned.
>
> The 5 in
>
> ice-9/eval.scm:619:8: Throw to key `sqlite-error' with args `(#f 5 "datab=
ase is locked")'.=20=20
>                                                                  ^^
>
> 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 accum=
ulated,
> and only then give up.

Indeed, that=E2=80=99s actually what nix/libstore does.

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

Awesome.

I=E2=80=99ve merged these guile-sqlite3 bits and added a =E2=80=9CPRAGMA bu=
sy_timeout=E2=80=9D
in Cuirass (the pragma allows us to set the timeout even when using an
older guile-sqlite3.)  I=E2=80=99ve updated the =E2=80=98cuirass=E2=80=99 p=
ackage and will test
soonish on berlin.

Thank you!

Ludo=E2=80=99.