From: "Clément Lassieur" <clement@lassieur.org>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: 32234@debbugs.gnu.org
Subject: bug#32234: [PATCH 2/2] database: Serialize all database accesses in a thread.
Date: Sun, 26 Aug 2018 16:07:12 +0200 [thread overview]
Message-ID: <87lg8tb4rz.fsf@lassieur.org> (raw)
In-Reply-To: <87zhxih2no.fsf@gnu.org>
Hi Ludovic,
Ludovic Courtès <ludo@gnu.org> writes:
> Excellent, thanks for working on this! This looks great to me, and I
> think the pros outweigh the cons. Did you check on a big database how
> well it performs?
Yes, I didn't see any difference. When I use Berlin's database, it
works well but crashes quickly for another reason (lack of disk space I
think, and /tmp being tmpfs).
> One comment:
>
>> -(define* (handle-build-event db event)
>> +(define* (handle-build-event event)
>> "Handle EVENT, a build event sexp as produced by 'build-event-output-port',
>> -updating DB accordingly."
>> +updating the database accordingly."
>
> [...]
>
>> +(define %db-channel
>> + (make-parameter #f))
>> +
>> +(define-syntax-rule (with-db-critical-section db exp ...)
>> + "Evaluate EXP... in the critical section corresponding to %DB-CHANNEL.
>> +DB is bound to the argument of that critical section: the database
>> +connection."
>> + (call-with-critical-section (%db-channel)
>> + (lambda (db) exp ...)))
>> +
>
> I think I find it nicer to keep the ‘db’ parameter everywhere (except
> that it’s now a channel instead of an actual database) rather than using
> this global variable.
>
> WDYT?
That 'db' parameter made sense before, because there were different
database connections: one per fiber. But now that there is only one
global channel accessible from everywhere, I can't find any use for a
'db-channel' parameter.
Also, using two differents channels for the same database would be a
bug, it would break the serialization mechanism.
And I don't think using several databases (with one channel per
database) would make sense either.
WDYT?
next prev parent reply other threads:[~2018-08-26 14:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-21 9:57 bug#32234: Cuirass: The SQLite built in busy handler might block the Fibers scheduler Clément Lassieur
2018-07-23 9:18 ` Ludovic Courtès
2018-07-23 13:42 ` Clément Lassieur
2018-07-23 14:57 ` Ludovic Courtès
2018-07-23 16:18 ` Clément Lassieur
2018-07-23 20:11 ` Ludovic Courtès
2018-08-06 19:27 ` bug#32234: [PATCH 1/2] utils: Avoid deadlock when WITH-CRITICAL-SECTION calls are nested Clément Lassieur
2018-08-06 19:27 ` bug#32234: [PATCH 2/2] database: Serialize all database accesses in a thread Clément Lassieur
2018-08-06 19:35 ` Clément Lassieur
2018-08-19 14:06 ` Ludovic Courtès
2018-08-26 14:07 ` Clément Lassieur [this message]
2018-08-26 21:16 ` Ludovic Courtès
2018-08-27 13:47 ` Clément Lassieur
2018-08-27 12:41 ` Danny Milosavljevic
2018-08-27 13:18 ` Clément Lassieur
2018-08-27 14:23 ` Danny Milosavljevic
2018-08-27 15:05 ` Clément Lassieur
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