From bdf860c2e99077d431da0cc1db4fc14db2a35d31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Fri, 21 Dec 2018 23:35:20 +0100
Subject: [PATCH] database: Use "write-ahead log" mode and set a long "busy
timeout".
This should avoid "database is locked" errors when there's a lot of
concurrency, for instance when offloading simultaneously a lot of
builds.
* guix/store/database.scm (call-with-database): Add two 'sqlite-exec'
calls to set 'journal_mode' and 'busy_timeout'.
---
guix/store/database.scm | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/guix/store/database.scm b/guix/store/database.scm
index e6bfbe763e9..4791f498654 100644
--- a/guix/store/database.scm
+++ b/guix/store/database.scm
@@ -79,6 +79,15 @@ (define (call-with-database file proc)
create it and initialize it as a new database."
(let ((new? (not (file-exists? file)))
(db (sqlite-open file)))
+ ;; Turn DB in "write-ahead log" mode, which should avoid SQLITE_LOCKED
+ ;; errors when we have several readers: <https://www.sqlite.org/wal.html>.
+ (sqlite-exec db "PRAGMA journal_mode=WAL;")
+
+ ;; Install a busy handler such that, when the database is locked, sqlite
+ ;; retries until 30 seconds have passed, at which point it gives up and
+ ;; throws SQLITE_BUSY.
+ (sqlite-exec db "PRAGMA busy_timeout = 30000;")
+
(dynamic-wind noop
(lambda ()
(when new?
--
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