Quit when processlist is too long

include/dbm.php

@@ -15,12 +15,14 @@ class dbm {
 		// updating
 
 		$statelist = "";
+		$processes = 0;
 		foreach ($states AS $state => $usage) {
 			if ($statelist != "")
 				$statelist .= ", ";
 			$statelist .= $state.": ".$usage;
+			++$processes;
 		}
-		return($statelist);
+		return(array("list" => $statelist, "amount" => $processes));
 	}
 }
 ?>

include/poller.php

@@ -28,8 +28,11 @@ function poller_run(&$argv, &$argc){
 	};
 
 	$processlist = dbm::processlist();
-	if ($processlist != "")
+	if ($processlist["list"] != "") {
-		logger("Processlist: ".$processlist, LOGGER_DEBUG);
+		logger("Processes: ".$processlist["amount"]." - Processlist: ".$processlist["list"], LOGGER_DEBUG);
+		if ($processlist["amount"] > 5)
+			return;
+	}
 
 	if (poller_max_connections_reached())
 		return;
@@ -66,8 +69,11 @@ function poller_run(&$argv, &$argc){
 
 		// Log the type of database processes
 		$processlist = dbm::processlist();
-		if ($processlist != "")
+		if ($processlist["amount"] != "") {
-			logger("Processlist: ".$processlist, LOGGER_DEBUG);
+			logger("Processes: ".$processlist["amount"]." - Processlist: ".$processlist["list"], LOGGER_DEBUG);
+			if ($processlist["amount"] > 5)
+				return;
+		}
 
 		// Constantly check the number of available database connections to let the frontend be accessible at any time
 		if (poller_max_connections_reached())

index.php

@@ -55,8 +55,14 @@ if(!$install) {
 	load_config('system');
 
 	$processlist = dbm::processlist();
-	if ($processlist != "")
+	if ($processlist["list"] != "") {
-		logger("Processlist: ".$processlist, LOGGER_DEBUG);
+		logger("Processes: ".$processlist["amount"]." - Processlist: ".$processlist["list"], LOGGER_DEBUG);
+
+		// More than 20 running database processes?
+		// The system is too busy, so quit.
+		if ($processlist["amount"] > 20)
+			system_unavailable();
+	}
 
 	$maxsysload_frontend = intval(get_config('system','maxloadavg_frontend'));
 	if($maxsysload_frontend < 1)