Memcached::addServers

(PECL memcached >= 0.1.1)

Memcached::addServers — Ajoute plusieurs serveurs au pool

Description

public Memcached::addServers(array $servers): bool

Memcached::addServers() ajoute les serveurs servers au pool de serveurs. Chaque entrée dans servers doit être un tableau, contenant le nom d'hôte, et optionnellement son poids. Aucune connexion n'est établie au serveur à ce moment-là.

Le même serveur peut apparaître plusieurs fois dans le pool, car aucune vérification de duplication n'est faite. Ce n'est pas recommandé. Au lieu de cela, il vaut mieux utiliser le paramètre weight pour augmenter le poids du serveur.

Liste de paramètres

array: Un tableau de serveurs à ajouter.

Valeurs de retour

Cette fonction retourne true en cas de succès ou false si une erreur survient.

Exemples

Exemple #1 Exemple avec Memcached::addServers()

<?php
$m = new Memcached();

$servers = array(
    array('mem1.domain.com', 11211, 33),
    array('mem2.domain.com', 11211, 67)
);
$m->addServers($servers);
?>

Voir aussi

Memcached::addServer() - Ajoute un serveur au pool
Memcached::resetServerList() - Supprime tous les serveurs depuis la liste des serveurs

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User Contributed Notes 2 notes

down

Aliaser ¶

8 years ago

For a proper FailOver mechanism:

$memcached = new Memcached();
$memcached->setOption(Memcached::OPT_CONNECT_TIMEOUT, 10);
$memcached->setOption(Memcached::OPT_DISTRIBUTION, Memcached::DISTRIBUTION_CONSISTENT);
$memcached->setOption(Memcached::OPT_SERVER_FAILURE_LIMIT, 2);
$memcached->setOption(Memcached::OPT_REMOVE_FAILED_SERVERS, true);
$memcached->setOption(Memcached::OPT_RETRY_TIMEOUT, 1);
$memcached->addServers($servers);

Memcached::OPT_DISTRIBUTION: set it to consistent hashing. If one memcached node is dead, its keys (and only its keys) will be evenly distributed to other nodes. This is where the magic is done. This is really different from removing one server in your ->addServers() call.

Memcached::OPT_SERVER_FAILURE_LIMIT: number of connection issues before a server is marked as DEAD, and removed from the list of servers (default: 5).

Memcached::OPT_REMOVE_FAILED_SERVERS: set it to «true», to enable the removal of dead servers.

Memcached::OPT_RETRY_TIMEOUT: after a node is declared DEAD, libmemcached will try it again after that many seconds. Here I've set it to 1 second, but I'm working on PHP scripts that run for less than 100ms most of the time. That would only be useful for cron/daemonize scripts.

Memcached::OPT_CONNECT_TIMEOUT: the timeout after which a server is considered DEAD. As my servers are on the same LAN, ping is ~0.5ms, so 10ms is large enough to consider the server is DEAD. Note that you have to wait twice that time before a node is marked DEAD, so if it's 1000ms, your script will lock for 2 seconds before ignoring the DEAD server. That may affect your response times a lot, and that's why I've set it very low

Author of this is Yvan from Dugwood

down

Michael Brenden ¶

13 years ago

See the note for __construct()

Important to not call ->addServers() every run -- only call it if no servers exist (check getServerList() ); otherwise, since addServers() does not check for dups, it will let you add the same server again and again and again, resultings in hundreds if not thousands of connections to the MC daemon.

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