Aaron Schulz has uploaded a new change for review.
https://gerrit.wikimedia.org/r/314340
Change subject: Make LoadMonitor use $serverIndexes in the cache key
......................................................................
Make LoadMonitor use $serverIndexes in the cache key
* This avoids collisions of generic and custom LB group
server list keys, which could cause warnings and errors.
* Remove $group param from scaleLoads(), which was unused
and less robust for making keys anyway.
* Remove clearCaches() method, which only had one caller
in a script that printed lag times in a loop. Its not
worth keeping and having to pass in the server index
list.
* Also guard scaleLoads() against recent server additions.
Bug: T147359
Change-Id: Idd15f0bebb68782fda36f483880cf7fe9673b940
---
M includes/libs/rdbms/loadbalancer/ILoadBalancer.php
M includes/libs/rdbms/loadbalancer/LoadBalancer.php
M includes/libs/rdbms/loadmonitor/ILoadMonitor.php
M includes/libs/rdbms/loadmonitor/LoadMonitor.php
M includes/libs/rdbms/loadmonitor/LoadMonitorNull.php
M maintenance/lag.php
6 files changed, 24 insertions(+), 41 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/mediawiki/core
refs/changes/40/314340/1
diff --git a/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
b/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
index aa7d1b4..e5ed2f1 100644
--- a/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/ILoadBalancer.php
@@ -518,13 +518,6 @@
public function safeWaitForMasterPos( IDatabase $conn, $pos = false,
$timeout = null );
/**
- * Clear the cache for slag lag delay times
- *
- * This is only used for testing
- */
- public function clearLagTimeCache();
-
- /**
* Set a callback via IDatabase::setTransactionListener() on
* all current and future master connections of this load balancer
*
diff --git a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
index 31c022c..9f1021d 100644
--- a/includes/libs/rdbms/loadbalancer/LoadBalancer.php
+++ b/includes/libs/rdbms/loadbalancer/LoadBalancer.php
@@ -301,7 +301,7 @@
}
# Scale the configured load ratios according to the dynamic
load if supported
- $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group,
$domain );
+ $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $domain );
$laggedReplicaMode = false;
@@ -1469,10 +1469,6 @@
}
return $ok;
- }
-
- public function clearLagTimeCache() {
- $this->getLoadMonitor()->clearCaches();
}
public function setTransactionListener( $name, callable $callback =
null ) {
diff --git a/includes/libs/rdbms/loadmonitor/ILoadMonitor.php
b/includes/libs/rdbms/loadmonitor/ILoadMonitor.php
index 72a8785..14a52c5 100644
--- a/includes/libs/rdbms/loadmonitor/ILoadMonitor.php
+++ b/includes/libs/rdbms/loadmonitor/ILoadMonitor.php
@@ -41,12 +41,12 @@
);
/**
- * Perform pre-connection load ratio adjustment.
- * @param int[] &$weightByServer Map of (server index => integer weight)
- * @param string|bool $group The selected query group. Default: false
- * @param string|bool $domain Default: false
+ * Perform load ratio adjustment before deciding which server to use
+ *
+ * @param int[] &$weightByServer Map of (server index => float weight)
+ * @param string|bool $domain
*/
- public function scaleLoads( array &$weightByServer, $group = false,
$domain = false );
+ public function scaleLoads( array &$weightByServer, $domain );
/**
* Get an estimate of replication lag (in seconds) for each server
@@ -55,14 +55,7 @@
*
* @param integer[] $serverIndexes
* @param string $domain
- *
* @return array Map of (server index => float|int|bool)
*/
public function getLagTimes( array $serverIndexes, $domain );
-
- /**
- * Clear any process and persistent cache of lag times
- * @since 1.27
- */
- public function clearCaches();
}
diff --git a/includes/libs/rdbms/loadmonitor/LoadMonitor.php
b/includes/libs/rdbms/loadmonitor/LoadMonitor.php
index 60400e3..499542d 100644
--- a/includes/libs/rdbms/loadmonitor/LoadMonitor.php
+++ b/includes/libs/rdbms/loadmonitor/LoadMonitor.php
@@ -40,7 +40,7 @@
/** @var float Moving average ratio (e.g. 0.1 for 10% weight to new
weight) */
private $movingAveRatio;
- const VERSION = 1;
+ const VERSION = 1; // cache key version
public function __construct(
ILoadBalancer $lb, BagOStuff $srvCache, BagOStuff $cache, array
$options = []
@@ -59,12 +59,17 @@
$this->replLogger = $logger;
}
- public function scaleLoads( array &$weightByServer, $group = false,
$domain = false ) {
+ public function scaleLoads( array &$weightByServer, $domain ) {
$serverIndexes = array_keys( $weightByServer );
$states = $this->getServerStates( $serverIndexes, $domain );
$coefficientsByServer = $states['weightScales'];
foreach ( $weightByServer as $i => $weight ) {
- $weightByServer[$i] = $weight *
$coefficientsByServer[$i];
+ if ( isset( $coefficientsByServer[$i] ) ) {
+ $weightByServer[$i] = $weight *
$coefficientsByServer[$i];
+ } else { // server recently added to config?
+ $host = $this->parent->getServerName( $i );
+ $this->replLogger->error( __METHOD__ . ": host
$host not in cache" );
+ }
}
}
@@ -75,15 +80,16 @@
}
protected function getServerStates( array $serverIndexes, $domain ) {
- if ( count( $serverIndexes ) == 1 && reset( $serverIndexes ) ==
0 ) {
+ $writerIndex = $this->parent->getWriterIndex();
+ if ( count( $serverIndexes ) == 1 && reset( $serverIndexes ) ==
$writerIndex ) {
# Single server only, just return zero without caching
return [
- 'lagTimes' => [ $this->parent->getWriterIndex()
=> 0 ],
- 'weightScales' => [
$this->parent->getWriterIndex() => 1 ]
+ 'lagTimes' => [ $writerIndex => 0 ],
+ 'weightScales' => [ $writerIndex => 1.0 ]
];
}
- $key = $this->getCacheKey();
+ $key = $this->getCacheKey( $serverIndexes );
# Randomize TTLs to reduce stampedes (4.0 - 5.0 sec)
$ttl = mt_rand( 4e6, 5e6 ) / 1e6;
# Keep keys around longer as fallbacks
@@ -191,18 +197,14 @@
return $conn ? 1.0 : 0.0;
}
- public function clearCaches() {
- $key = $this->getCacheKey();
- $this->srvCache->delete( $key );
- $this->mainCache->delete( $key );
- }
-
- private function getCacheKey() {
+ private function getCacheKey( array $serverIndexes ) {
+ sort( $serverIndexes );
// Lag is per-server, not per-DB, so key on the master DB name
return $this->srvCache->makeGlobalKey(
'lag-times',
self::VERSION,
- $this->parent->getServerName(
$this->parent->getWriterIndex() )
+ $this->parent->getServerName(
$this->parent->getWriterIndex() ),
+ implode( '-', $serverIndexes )
);
}
}
diff --git a/includes/libs/rdbms/loadmonitor/LoadMonitorNull.php
b/includes/libs/rdbms/loadmonitor/LoadMonitorNull.php
index 67bac2b..5e64f82 100644
--- a/includes/libs/rdbms/loadmonitor/LoadMonitorNull.php
+++ b/includes/libs/rdbms/loadmonitor/LoadMonitorNull.php
@@ -30,7 +30,7 @@
public function setLogger( LoggerInterface $logger ) {
}
- public function scaleLoads( array &$loads, $group = false, $domain =
false ) {
+ public function scaleLoads( array &$loads, $domain = false ) {
}
diff --git a/maintenance/lag.php b/maintenance/lag.php
index 9d92794..fa2bd54 100644
--- a/maintenance/lag.php
+++ b/maintenance/lag.php
@@ -48,7 +48,6 @@
echo "\n";
while ( 1 ) {
- $lb->clearLagTimeCache();
$lags = $lb->getLagTimes();
unset( $lags[0] );
echo gmdate( 'H:i:s' ) . ' ';
--
To view, visit https://gerrit.wikimedia.org/r/314340
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: Idd15f0bebb68782fda36f483880cf7fe9673b940
Gerrit-PatchSet: 1
Gerrit-Project: mediawiki/core
Gerrit-Branch: master
Gerrit-Owner: Aaron Schulz <asch...@wikimedia.org>
_______________________________________________
MediaWiki-commits mailing list
MediaWiki-commits@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/mediawiki-commits
