From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 16 Apr 2013 19:43:04 +0000 (-0700)
Subject: Reduced DB contention in User::saveOptions().
X-Git-Tag: 1.31.0-rc.0~19979^2
X-Git-Url: https://git.cyclocoop.org/%7B%24www_url%7Dadmin/compta/exercices/journal.php?a=commitdiff_plain;h=dc0fae6f6a98b7b9dcadefed688825165d0ae1d6;p=lhc%2Fweb%2Fwiklou.git

Reduced DB contention in User::saveOptions().

Change-Id: Ic91501cd6476dae54b54b85f2f06c25bd2577c9b
---

diff --git a/includes/User.php b/includes/User.php
index ed97deb2e7..eda8bc9d7d 100644
--- a/includes/User.php
+++ b/includes/User.php
@@ -4428,8 +4428,18 @@ class User {
 		}
 
 		$dbw = wfGetDB( DB_MASTER );
-		$dbw->delete( 'user_properties', array( 'up_user' => $userId ), __METHOD__ );
-		$dbw->insert( 'user_properties', $insert_rows, __METHOD__ );
+		$hasRows = $dbw->selectField( 'user_properties', '1',
+			array( 'up_user' => $userId ), __METHOD__ );
+
+		if ( $hasRows ) {
+			// Only do this delete if there is something there. A very large portion of
+			// calls to this function are for setting 'rememberpassword' for new accounts.
+			// Doing this delete for new accounts with no rows in the table rougly causes
+			// gap locks on [max user ID,+infinity) which causes high contention since many
+			// updates will pile up on each other since they are for higher (newer) user IDs.
+			$dbw->delete( 'user_properties', array( 'up_user' => $userId ), __METHOD__ );
+		}
+		$dbw->insert( 'user_properties', $insert_rows, __METHOD__, array( 'IGNORE' ) );
 	}
 
 	/**