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eZ Publish (5.x)

eZ Publish 5.x | For eZ Platform & eZ Studio topics see Technical manual and User manual, for eZ Publish 4.x and Legacy topics see eZ Publish legacy

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Current implementation uses a caching library called Stash (, via Stash-bundle. If this changes, then the configuration format will most likely change as well.). Stash supports the following cache handlersbackends: FileSystemMemcache, APC, Sqlite, XCacheRedis and BlackHole.

Use of Memcached or Redis is a requirement for use in Clustering setup, for overview of clustering feature see Clustering

If eZ Publish Platform changes to another cache system, configuration will change in the future, changes to configuration in StashBundle is listed here:

titleConfiguration change in 5.4/2014.07

StashBundle version bundled with 5.4/2014.07 and higher refers to cache backends as "drivers" where it was previously referred to as "handlers" in yml configuration

Cache service

The cache system is exposed as a "cache" service, and can be reused by any other service as described on the Persistence cache page.


Code Block
titleDefault ezpublish.yml
            # For eZ Publish Platform versions prior to 5.4/2014.07, use "handlers" instead of "drivers"!
                - FileSystem
            inMemory: false
            registerDoctrineAdapter: false


Code Block
            # For eZ Publish Platform versions prior to 5.4/2014.07, use "handlers" instead of "drivers"!
                - BlackHole
            inMemory: true
            registerDoctrineAdapter: false


If you want to change to another handlercache backend, see in Stash handlers backend configuration below for what kind of settings you have available.

titleNote for "inMemory" cache with long running scripts

Use of inMemory caching with BlackHole or any other cache handler backend should not be used for long running scripts as it will over time return stale data, inMemory cache is not shared across requests/processes, so invalidation does not happen!


Code Block
titleezpublish.yml site group setting
            cache_pool_name: "default"

The "default" here refers to the name of the cache pool as specified in the stash configuration block shown above, if your install has several repositories (databases), then make sure every group of sites using different repositories also uses a different cache pool to avoid unwanted effects.
NB: We plan to make this more native in the future, so this setting will someday not be needed.



cache backend configuration

General settings

To check which cache settings are available for your installation, run the following command in your terminal :

Code Block
php ezpublish/console config:dump-reference stash


This cache handler backend is using local filesystem, by default the Symfony cache folder, as this is per server, it does not support multi server (cluster) setups!

We strongly discourage you from storing cache files on NFS, as it defeats the purpose of the cache: speed

Available settings

The path where the cache is placed, default is %kernel.cache_dir%/stash, effectively ezpublish/cache/<env>/stash
Number of times the cache key should be split up to avoid having to many files in each folder, default is 2.
The permissions of the cache file, default is 0660.
The permission of the cache file directories (see dirSplit), default is 0770.

Limit on how many key to path entries are kept in memory during execution at a time to avoid having to recalculate the path on key lookups, default 200.



Algorithm used for creating paths, default md5. Use crc32 on Windows to avoid path length issues.
titleIssues with Microsoft Windows

If you are using a Windows OS, you may encounter an issue regarding long paths for cache directory name. The paths are long because Stash uses md5 to generate unique key that are sanitized really quickly.

Solution is to change the hash algorithm used by Stash.

Code Block
titleSpecifying key hash function
            # For eZ Publish Platform versions prior to 5.4/2014.07, use "handlers" instead of "drivers"!
                - FileSystem
            inMemory: true
            registerDoctrineAdapter: false
                keyHashFunction: 'crc32'

This configuration is only recommended for Windows users.

Note: You can also define the path where you want the cache files to be generated to be able to get even shorter system path for cache files.


FileSystem cache backend troubleshooting

By default, Stash Filesystem cache backend stores cache to a sub-folder named after the environment (i.e. ezpublish/cache/devezpublish/cache/prod). This can lead to the following issue : if different environments are used for operations, persistence cache (manipulating content, mostly) will be affected and cache can become inconsistent.

To prevent this, there are 2 solutions :

  1. Manual

    Always use the same environment, for web, command line, cronjobs...

  2. Share stash cache across Symfony environments (prod / dev)

Either by using another Stash cache backend, or by setting Stash to use a shared cache folder that does not depend on the environment. 
In ezpublish.yml:

Code Block
                path: "%kernel.root_dir%/cache/common"

This will store stash cache to ezpublish/cache/common.


This cache backend is using shard memory using APC's user cache feature, as this is per server, it does not support multi server (cluster) setups, unless you use PHP-FPM on a dedicated server (this way, user cache can be shared among all the workers in one pool).


As APC user cache is not shared between processes, it is not possible to clear the user cache from CLI, even if you set apc.enable_cli to On.
Hence publishing content from a command line script won't let you properly clear SPI Persistence cache.

Please also note that the default value for apc.shm_size is 128MB. However, 256MB is recommended for APC to work properly. For more details please refer to the APC configuration manual.


ttlThe time to live of the cache in seconds, default set to 500 (8.3 minutes)
namespaceA namespace to prefix cache keys with to avoid key conflicts with other eZ Publish sites on same eZ Publish installation, default is null.


This cache handler backend is using Memcached, a distributed caching solution, this is the only supported cache solution for multi server (cluster) setups!


Stash supports both the php Memcache and Memcached -memcache and php-memcached extensions. However Memcached is recommended as it is much more advanced and supports all settings below. only php-memcache is officially tested on Redhat/Centos while php-memcached is on Debian and Ubuntu. If you have both extensions installed, Stash will automatically choose Memcachedphp-memcached.


Array of Memcached servers, with host/IP, port and weight

server: Host or IP of your Memcached server
port: Port where Memcached is listening to (defaults to 11211)
weight: Weight of the server, when using several Memcached servers

prefix_keyA namespace to prefix cache keys with to avoid key conflicts with other eZ Publish sites on same eZ Publish installation (default is an empty string).
Must be the same on all server with the same installation. See Memcached prefix_key option.
compressiondefault true. See Memcached compression option.
libketama_compatibledefault false. See Memcached libketama_compatible option
buffer_writesdefault false. See Memcached buffer_writes option 
binary_protocoldefault false. See Memcached binary_protocol option 
no_blockdefault false. See Memcached no_block option 
tcp_nodelaydefault false. See Memcached tcp_nodelay option 
connection_timeoutdefault 1000. See Memcached connection_timeout option 
retry_timeoutdefault 0. See Memcached retry_timeout option 
send_timeoutdefault 0. See Memcached send_timeout option 

default 0. See Memcached recv_timeout option 

poll_timeoutdefault 1000. See Memcached poll_timeout option 
cache_lookupsdefault false. See Memcached cache_lookups option 
server_failure_limitdefault 0. See PHP Memcached documentation
See Memcached socket_send_size option 


. ✲ ✸
socket_recv_sizeSee Memcached socket_recv_size option. ✲ ✸
serializerSee Memcached serializer option. ✲ ✸
hashSee Memcached hash option. ✲ ✸

Specifies the method of distributing item keys to the servers. See Memcached distribution option. ✲ ✸


✲ All settings but servers are only available with memcached php extension, for more information on these settings and which version of php-memcached they are available in, see:


When using Memcache handler, it's strongly recommended to also use inMemory cache (see example below).
This will help reducing network traffic between your webserver and your Memcached server.

 If you are on eZ Publish 5.1, make sure to update Stash and StashBundle to get access to these settings.


Example with Memcache

Code Block
            # For eZ Publish Platform versions prior to 5.4/2014.07, use "handlers" instead of "drivers"!
            drivers: [ Memcache ]
            inMemory: true
            registerDoctrineAdapter: false
                prefix_key: ezdemo_
                retry_timeout: 1
                        port: 11211
titleConnection errors issue

If memcached does display connection errors when using the default (ascii) protocol, switching to binary protocol (in the stash configuration and memcached daemon) should resolve the issue.

Memory consumption issues with Redis

title>= 5.4.13

If you use the Redis cache driver and encounter problems with high memory consumption, you can use the following (non-SiteAccess-aware) settings:

Code Block
        igbinary: true/false
        lzf: true/false
  • ezpublish.stash_cache.igbinary enables you to use the igbinary PHP extension to serialize objects stored in cache.
    • Recommended enabled in most use cases.
  • ezpublish.stash_cache.lzf enables you to use the LZF PHP extension to compress serialized objects stored in cache.
    • Compression consumes some more CPU. A scenario where it improves overall performance is when Redis memory and/or network bandwidth is limited, with spare CPU capacity on PHP server.

These options in combination results in around 1/2 memory usage for API caching compared to not being enabled, igbinary accounts for ~75% of that and LZF the remaining ~25% when configured for max compression.

After changing these settings you need to clear cache and purge Redis content .