Caching config manual

Using RAM caching

The kernel version 8.5.1 supports both disk and shared memory caching.

PHP accelerator supports API handling of shared memory. It means that all web server processes can read and write into single address space. This allows to organize shared synchorouns cache.

Although the app data caching performed into a file at the file system level, sometimes (e. g. backup copying) there are cases when this cache is removed and becomes useless for further use.

The advantage of shared accelerator cache is its location within RAM. Using of swap indicates the inadequate hosting setup. The disadvantage of the swap file - its full reset when server is re-started.

PHP apps

The software app Description Version
APC Uses the available shared memory features. Provides the following PHP features for programming: apc_fetch, apc_store and apc_delete.
  • Disadvantage 1: uses shared memory for scripts and cache.
  • Disadvantage 2: data serialization is required when caching.

eAccelerator When creating a distributive, specify "--with-eaccelerator-shared-memory". It has the same disadvantages as the APC. Advantage: cache saving onto the disk can be configured.

Note. eAccelerator is incompatible with PHP version higher than 5.3

Is not supported from version 15.5.0

Memcached daemon

Aside from accelerators, a similar feature-rich memcached daemon is available.

It is a separate process that uses TCP/IP protocol for communications. It can support distributed, shared, synchronous cache. More than one server can be connected to the server with launched memcached. Using memcached solves accelerator cache problems, but the reduced performance due protocol transfer is a priority as well.

Example of operation with memcached on Ubuntu. Installation:

aptitude install memcached

Daemon settings are properly documented and located in the file /etc/memcached.conf

Daemon launch:

/etc/init.d/memcached start

There are three extensions for PHP to work with memcached server. When using memcache, unixsocket can be connected to it via:

define("BX_MEMCACHE_HOST", "unix:///path/to/memcached.sock"); 
define("BX_MEMCACHE_PORT", "0");

However, pre-configured memcached is required to work via sockets. To do it, go to memcached settings file and modify OPTIONS="" string to OPTIONS="-s /tmp/memcached.sock -a 00755". Only after that, modifications can be made to dbconn.php.

Bitrix24 config

Cache management is perfumed via constants, defined in the file dbconn.php (In kernel version higher than 14.0 settings are performed in other files).

Constant Description
BX_CACHE_TYPE The most important constant. In can the following values:
  • files - use as a drive cache storage. It has fully compatible behaviour. This specific type of cache is used in case of unsuccessful attempts to enable other types of cache.
  • memcache - connect to memcached to save cache. It is enabled only when a downloaded "memcache" extension is available as well as with established server connection.
  • eaccelerator - use eAccelerator shared Memory space as the storage. (Important! Starting from version 0.9.6, eAccelerator no longer supports user caching features. It means that for this version, the mechanism described here will not be working.)
  • apc - APC.
  • xcache - XCache.

 define("BX_CACHE_TYPE", "memcache");
BX_CACHE_SID Check if more than one Bitrix Site Manager instances are launched. This salt is added to all cache keys. It allows avoiding "confusion" between them.

define("BX_CACHE_SID", $_SERVER["DOCUMENT_ROOT"]."#01");
BX_MEMCACHE_HOST Required only if memcache is used. It determines the server URL with launched memcached daemon.

 define("BX_MEMCACHE_HOST", ""); 
BX_MEMCACHE_PORT Optional, has the value 11211 by default.

Note. The system checks the parameter eaccelerator.shm_max is set to non-zero value.

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