From 1bbfb2a313f74f753d71604683c6aef9c1e09662 Mon Sep 17 00:00:00 2001
From: Tim Starling <tstarling@users.mediawiki.org>
Date: Tue, 12 Jul 2011 08:08:58 +0000
Subject: [PATCH] Non-concurrent pop_type() since the $row === false case was
 being hit 99% of the time on WMF in a backlog situation.

---
 includes/job/JobQueue.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/includes/job/JobQueue.php b/includes/job/JobQueue.php
index 953d5869a4..0d917ba3e6 100644
--- a/includes/job/JobQueue.php
+++ b/includes/job/JobQueue.php
@@ -56,15 +56,18 @@ abstract class Job {
 
 		$dbw = wfGetDB( DB_MASTER );
 
+		$dbw->begin();
+
 		$row = $dbw->selectRow(
 			'job',
 			'*',
 			array( 'job_cmd' => $type ),
 			__METHOD__,
-			array( 'LIMIT' => 1 )
+			array( 'LIMIT' => 1, 'FOR UPDATE' )
 		);
 
 		if ( $row === false ) {
+			$dbw->commit();
 			wfProfileOut( __METHOD__ );
 			return false;
 		}
-- 
2.20.1