Removed unused postConnectionBackoff() from LoadMonitor

* This setting proved to be not terrible useful

Change-Id: I58b18947ff0edb8937229d0f130d7d10e846125e

diff --git a/RELEASE-NOTES-1.23 b/RELEASE-NOTES-1.23
index 3db4a91..6783170 100644 (file)
--- a/RELEASE-NOTES-1.23
+++ b/RELEASE-NOTES-1.23
@@ -31,6 +31,7 @@ production.
 * $wgPasswordSenderName has been deprecated. To set a custom mailer name,
   the system message 'emailsender' should be modified (default: "{{SITENAME}}").
 * $wgDBAhandler was removed as the only class using it was also removed
+* The 'max threads' setting was removed from $wgDBservers.
 
 === New features in 1.23 ===
 * ResourceLoader can utilize the Web Storage API to cache modules client-side.

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 4f93401..04ac106 100644 (file)
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -1654,7 +1654,6 @@ $wgSharedTables = array( 'user', 'user_properties' );
  *                                    if available
  *
  *   - max lag:     (optional) Maximum replication lag before a slave will taken out of rotation
- *   - max threads: (optional) Maximum number of running threads
  *
  *   These and any other user-defined properties will be assigned to the mLBInfo member
  *   variable of the Database object.

diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index c88ad05..7d0fe34 100644 (file)
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -188,7 +188,7 @@ class LoadBalancer {
         * @return bool|int|string
         */
        function getReaderIndex( $group = false, $wiki = false ) {
-               global $wgReadOnly, $wgDBClusterTimeout, $wgDBAvgStatusPoll, $wgDBtype;
+               global $wgReadOnly, $wgDBtype;
 
                # @todo FIXME: For now, only go through all this for mysql databases
                if ( $wgDBtype != 'mysql' ) {
@@ -198,18 +198,13 @@ class LoadBalancer {
                if ( count( $this->mServers ) == 1 ) {
                        # Skip the load balancing if there's only one server
                        return 0;
-               } elseif ( $group === false and $this->mReadIndex >= 0 ) {
+               } elseif ( $group === false && $this->mReadIndex >= 0 ) {
                        # Shortcut if generic reader exists already
                        return $this->mReadIndex;
                }
 
                wfProfileIn( __METHOD__ );
 
-               $totalElapsed = 0;
-
-               # convert from seconds to microseconds
-               $timeout = $wgDBClusterTimeout * 1e6;
-
                # Find the relevant load array
                if ( $group !== false ) {
                        if ( isset( $this->mGroupLoads[$group] ) ) {
@@ -225,7 +220,7 @@ class LoadBalancer {
                        $nonErrorLoads = $this->mLoads;
                }
 
-               if ( !$nonErrorLoads ) {
+               if ( !count( $nonErrorLoads ) ) {
                        wfProfileOut( __METHOD__ );
                        throw new MWException( "Empty server array given to LoadBalancer" );
                }
@@ -235,93 +230,60 @@ class LoadBalancer {
 
                $laggedSlaveMode = false;
 
+               # No server found yet
+               $i = false;
                # First try quickly looking through the available servers for a server that
                # meets our criteria
-               do {
-                       $totalThreadsConnected = 0;
-                       $overloadedServers = 0;
-                       $currentLoads = $nonErrorLoads;
-                       while ( count( $currentLoads ) ) {
-                               if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
+               $currentLoads = $nonErrorLoads;
+               while ( count( $currentLoads ) ) {
+                       if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
+                               $i = ArrayUtils::pickRandom( $currentLoads );
+                       } else {
+                               $i = $this->getRandomNonLagged( $currentLoads, $wiki );
+                               if ( $i === false && count( $currentLoads ) != 0 ) {
+                                       # All slaves lagged. Switch to read-only mode
+                                       wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode\n" );
+                                       $wgReadOnly = 'The database has been automatically locked ' .
+                                               'while the slave database servers catch up to the master';
                                        $i = ArrayUtils::pickRandom( $currentLoads );
-                               } else {
-                                       $i = $this->getRandomNonLagged( $currentLoads, $wiki );
-                                       if ( $i === false && count( $currentLoads ) != 0 ) {
-                                               # All slaves lagged. Switch to read-only mode
-                                               wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode\n" );
-                                               $wgReadOnly = 'The database has been automatically locked ' .
-                                                       'while the slave database servers catch up to the master';
-                                               $i = ArrayUtils::pickRandom( $currentLoads );
-                                               $laggedSlaveMode = true;
-                                       }
-                               }
-
-                               if ( $i === false ) {
-                                       # pickRandom() returned false
-                                       # This is permanent and means the configuration or the load monitor
-                                       # wants us to return false.
-                                       wfDebugLog( 'connect', __METHOD__ . ": pickRandom() returned false\n" );
-                                       wfProfileOut( __METHOD__ );
-
-                                       return false;
-                               }
-
-                               wfDebugLog( 'connect', __METHOD__ . ": Using reader #$i: {$this->mServers[$i]['host']}...\n" );
-                               $conn = $this->openConnection( $i, $wiki );
-
-                               if ( !$conn ) {
-                                       wfDebugLog( 'connect', __METHOD__ . ": Failed connecting to $i/$wiki\n" );
-                                       unset( $nonErrorLoads[$i] );
-                                       unset( $currentLoads[$i] );
-                                       continue;
+                                       $laggedSlaveMode = true;
                                }
+                       }
 
-                               // Perform post-connection backoff
-                               $threshold = isset( $this->mServers[$i]['max threads'] )
-                                       ? $this->mServers[$i]['max threads'] : 0;
-                               $backoff = $this->getLoadMonitor()->postConnectionBackoff( $conn, $threshold );
-
-                               // Decrement reference counter, we are finished with this connection.
-                               // It will be incremented for the caller later.
-                               if ( $wiki !== false ) {
-                                       $this->reuseConnection( $conn );
-                               }
+                       if ( $i === false ) {
+                               # pickRandom() returned false
+                               # This is permanent and means the configuration or the load monitor
+                               # wants us to return false.
+                               wfDebugLog( 'connect', __METHOD__ . ": pickRandom() returned false\n" );
+                               wfProfileOut( __METHOD__ );
 
-                               if ( $backoff ) {
-                                       # Post-connection overload, don't use this server for now
-                                       $totalThreadsConnected += $backoff;
-                                       $overloadedServers++;
-                                       unset( $currentLoads[$i] );
-                               } else {
-                                       # Return this server
-                                       break 2;
-                               }
+                               return false;
                        }
 
-                       # No server found yet
-                       $i = false;
+                       wfDebugLog( 'connect', __METHOD__ .
+                               ": Using reader #$i: {$this->mServers[$i]['host']}...\n" );
 
-                       # If all servers were down, quit now
-                       if ( !count( $nonErrorLoads ) ) {
-                               wfDebugLog( 'connect', "All servers down\n" );
-                               break;
+                       $conn = $this->openConnection( $i, $wiki );
+                       if ( !$conn ) {
+                               wfDebugLog( 'connect', __METHOD__ . ": Failed connecting to $i/$wiki\n" );
+                               unset( $nonErrorLoads[$i] );
+                               unset( $currentLoads[$i] );
+                               continue;
                        }
 
-                       # Some servers must have been overloaded
-                       if ( $overloadedServers == 0 ) {
-                               throw new MWException( __METHOD__ . ": unexpectedly found no overloaded servers" );
+                       // Decrement reference counter, we are finished with this connection.
+                       // It will be incremented for the caller later.
+                       if ( $wiki !== false ) {
+                               $this->reuseConnection( $conn );
                        }
-                       # Back off for a while
-                       # Scale the sleep time by the number of connected threads, to produce a
-                       # roughly constant global poll rate
-                       $avgThreads = $totalThreadsConnected / $overloadedServers;
-                       $totalElapsed += $this->sleep( $wgDBAvgStatusPoll * $avgThreads );
-               } while ( $totalElapsed < $timeout );
-
-               if ( $totalElapsed >= $timeout ) {
-                       wfDebugLog( 'connect', "All servers busy\n" );
-                       $this->mErrorConnection = false;
-                       $this->mLastError = 'All servers busy';
+
+                       # Return this server
+                       break;
+               }
+
+               # If all servers were down, quit now
+               if ( !count( $nonErrorLoads ) ) {
+                       wfDebugLog( 'connect', "All servers down\n" );
                }
 
                if ( $i !== false ) {

diff --git a/includes/db/LoadMonitor.php b/includes/db/LoadMonitor.php
index 651c499..b6ba4f2 100644 (file)
--- a/includes/db/LoadMonitor.php
+++ b/includes/db/LoadMonitor.php
@@ -42,24 +42,6 @@ interface LoadMonitor {
         */
        function scaleLoads( &$loads, $group = false, $wiki = false );
 
-       /**
-        * Perform post-connection backoff.
-        *
-        * If the connection is in overload, this should return a backoff factor
-        * which will be used to control polling time. The number of threads
-        * connected is a good measure.
-        *
-        * If there is no overload, zero can be returned.
-        *
-        * A threshold thread count is given, the concrete class may compare this
-        * to the running thread count. The threshold may be false, which indicates
-        * that the sysadmin has not configured this feature.
-        *
-        * @param DatabaseBase $conn
-        * @param float $threshold
-        */
-       function postConnectionBackoff( $conn, $threshold );
-
        /**
         * Return an estimate of replication lag for each server
         *
@@ -78,9 +60,6 @@ class LoadMonitorNull implements LoadMonitor {
        function scaleLoads( &$loads, $group = false, $wiki = false ) {
        }
 
-       function postConnectionBackoff( $conn, $threshold ) {
-       }
-
        /**
         * @param array $serverIndexes
         * @param string $wiki
@@ -188,24 +167,4 @@ class LoadMonitorMySQL implements LoadMonitor {
 
                return $times;
        }
-
-       /**
-        * @param DatabaseBase|DatabaseMySQLBase $conn
-        * @param int $threshold
-        * @return int
-        */
-       function postConnectionBackoff( $conn, $threshold ) {
-               if ( !$threshold ) {
-                       return 0;
-               }
-               $status = $conn->getMysqlStatus( "Thread%" );
-               if ( $status['Threads_running'] > $threshold ) {
-                       $server = $conn->getProperty( 'mServer' );
-                       wfLogDBError( "LB backoff from $server - Threads_running = {$status['Threads_running']}\n" );
-
-                       return $status['Threads_connected'];
-               } else {
-                       return 0;
-               }
-       }
 }