To enable Memcached on your website hosted by Cloud Platform, you must install the Memcache API and Integration module in your codebase, and configure the module for use.
When configuring your website to use Memcached, be aware of the following considerations:
Do not edit the memcache_key_prefix
or memcache_servers
settings, as
Cloud Platform adds the correct values in Acquia-specific code defined by the
Acquia require line, or
otherwise available by default on Cloud Next. Altering these values
can cause unexpected behavior.
If your website uses either automated testing or the memcache_admin
submodule, you must enable the Memcache API and Integration module. Although Drupal 9 or
later does not require you to enable the module, Acquia recommends
enabling the module to receive notifications about module updates.
For more information about stampede protection and database locking, see Enabling stampede protection and moving locks into memory.
Important
Test any of the procedures provided on this page on a non-production environment before implementing them on the production environment.
In Cloud Next, Acquia routinely optimizes the non-production environment to ensure high performance and enhanced scalability of your application. Therefore, your non-production memcache storage might be emptied from time to time. Production-level memcache workloads are notified in advance according to Acquia’s communication policies.
For Memcached to function, you must provide additional configuration code that enables autoloading, and identifies Memcached as an alternative cache back-end.
To configure your website for Memcached, make the following changes to your codebase, depending on your subscription type:
Note
For environments running on Cloud Next technologies:
Memcache runs per-environment instead of per-server
and leverages mcrouter. Steps 2 and 3 are not required because
Memcache configuration logic is included automatically. To exclude
this logic on your environments, add the following line to your
settings.php
file:
define('AH_NO_MEMCACHE_INCLUDE', 1);
If you have the older cloud-memcache-d8+.php
file stored in this
repository, ensure that you delete it.
Download the Memcache API and Integration module, and then add
the module to your codebase in the modules/contrib/memcache
directory. We recommend to use Composer to install the module:
composer require drupal/memcache
Add the composer package that contains the Acquia Memcache settings to your project:
composer require acquia/memcache-settings
For each website that requires Memcached, edit the Cloud Platform
database require line in
settings.php
with a PHP require_once
statement,
similar to the following example:
if (file_exists('/var/www/site-php')) {
require('/var/www/site-php/mysite/mysite-settings.inc');
// Memcached settings for Acquia Hosting
$memcache_settings_file = DRUPAL_ROOT . "/../vendor/acquia/memcache-settings/memcache.settings.php";
if (file_exists($memcache_settings_file)) {
require_once $memcache_settings_file;
}
}
Rebuild caches by running the following command, replacing
[example.com]
with the domain name of your website:
drush cr --uri=[example.com]
Truncate all cache_
tables in the database for the website.
Memcache is now enabled for your website. Continue to read the next section.
If you need assistance, create a Support ticket.
Download the Memcache API and Integration module and add
the module to your codebase in the modules/contrib/memcache
directory. We recommend to use Composer to install the module:
composer require drupal/memcache
Download acsfd8+.memcache.settings.php
,
and then add it to the factory-hooks/post-settings-php
directory. For more information about the post-settings-php hook,
see Altering values in settings.php with hooks.
Rebuild caches by running the following command, replacing
[example.com]
with the domain name of your website:
drush cr --uri=[example.com]
Truncate all cache_
tables in the database for the website.
Memcache is now enabled for your website. If you need assistance, create a Support ticket.
For BLT users
BLT users that continue to experience issues should submit a ticket to the BLT issue queue.
If you are installing the module on a Drupal 7 website, you must enable the
module before modifying settings.php
, or you will receive a
ServiceNotFoundException:
error message.
Note
For Drupal 7 environments running on Cloud Next
technologies, step 2 isn’t required because Memcache configuration logic is
included automatically. To exclude this logic on your environments, add the
following line to your settings.php
file:
define('AH_NO_MEMCACHE_INCLUDE', 1);
To configure your Drupal 7 website for Memcached, make the following changes to your codebase, depending on your subscription type:
Download the Memcache API and Integration module, and then add
the module to your codebase in the
sites/all/modules/contrib/memcache
directory.
Download cloud-memcache-d7.php
, and
add the contents of the file to your website’s settings.php
file, after the Acquia database require line.
Clear caches by running the following command, replacing
[example.com]
with the domain name of your website:
drush cc all --uri=[example.com]
Truncate all cache_
tables in the database for the website.
Memcache is now enabled for your website. If you need assistance, create a Support ticket.
Download the Memcache API and Integration module, and then add
the module to your codebase in the
sites/all/modules/contrib/memcache
directory.
Download acsfd7.memcache.settings.php
,
and add it to the factory-hooks/post-settings-php
directory. For more information about the post-settings-php hook,
see Altering values in settings.php with hooks.
Edit the file, modifying the following lines if they do not correspond to the location of the Memcache API and Integration module in your codebase:
$conf['cache_backends'][] = 'sites/all/modules/contrib/memcache/memcache.inc';
$conf['lock_inc'] = 'sites/all/modules/contrib/memcache/memcache-lock.inc';
Clear caches by running the following command , replacing
[example.com]
with the domain name of your website:
drush cc all --uri=[example.com]
Truncate all cache_
tables in the database for the website.
Memcache is now enabled for your website. Continue to read the next section.
If you need assistance, create a Support ticket.
For environments running on Cloud Next technologies, you can adjust the memory allocated to Memcached by navigating to the Environment Settings page of the Cloud Platform user interface and selecting the Advanced tab.
For environments running on the Cloud Classic infrastructure, you must create a Support ticket to request that your Memcached memory allocation be modified. Larger amounts of memory can be allocated to Cloud Classic environments with dedicated Memcached infrastructure. Contact your Acquia account team for more information about this advanced configuration.
To allocate memory to Memcached on Cloud Platform Professional and enable it to run:
Sign in to the Cloud Platform user interface and select your application and environment.
In the navigation pane, click Infrastructure.
In the card for the web infrastructure, click the Configure link.
In the Memcached memory (MB) field, enter the amount of memory to allocate to Memcached. A value of 64 MB is the default value for applications running on Cloud Platform, but you may increase the value depending on the needs of your application.
Click Save.
You can leverage the Memcache binary protocol in Cloud Classic environments. However, Acquia does not recommend its use.
To use this protocol in Cloud Classic environments, ensure that you
enable the Memcached::OPT_TCP_NODELAY
flag in Memcache options to
avoid slow fetches of empty cache items.
The Memcache binary protocol is not supported in Cloud Next environments. Cloud Next leverages mcrouter, which only supports the ASCII protocol for Memcache. If you enable binary protocol in Cloud Next environments, Drupal and PHP cannot communicate with Memcache servers. Therefore, the application fails to set or get cache items but does not return an error message.