We will talk about choosing cache engines in a LAMP stack:
We briefly discussed a few of them with the modules. We will consider their usage now.
Code cleanup and performance tuning in PHP scripts goes only so far to make pages fast enough. Caching engines prevent a trip to the server for pages that are already available. Caching can be done for internally compiled PHP scripts, the generated output or the intermediary data processing objects.
APC is an opcode caching engine and comes with PECL/PEAR repository. The compiled code from the PHP runtime engine is stored in the shared memory for later access. It can be linked into the PHP code or as Dynamic Shared Object (DSO) and by specifying the extension as apc.so in the php.ini file
eAccelerator is a similar compiled-state PHP 4 caching engine and also optimizes as well as encodes code. The resulting can be distributed to those that have eAccelerator installed. Again the compiled objects are stored in shared memory and the different setting such as memory size, cache directory, time-to-live, prune period can be described in the php.ini file. The extension entry is accelerator.so Similarly Zend optimizer uses the native Zend engine that powers PHP to cache compile time objects.
JPCache works by storing the generated output of a PHP script or disk to disk or in SQL Server. It's written as a PHP library. In addition to caching, it also provides compression resulting in more improvements in page load time. Configuration options include those for the database, the credentials and the compression level.
Memcached is a distributed memory object caching system and is available as a PHP DSO. we can add entries to memcache using the add method that takes key values as parameters.
The get_stats() method on the memcache is particularly helpful and gives such information as current connections, total connections, hits, misses, current items, total items, etc.
As we see now, there are overlap between the caching frameworks. The complimentary ones could increase performance but others may not work well together.
JPCache and memcached can work well with other but because eAccelerator and Zend have their own encoders, they are mutually exclusive. Moreover, you only want one opcode caching. Memcached is a great choice for large objects and varied lifetime or small objects but frequent database access. If there are static pages, JPCache works well. If there is a lot of PHP code, then an opcode caching like APC works well.
We briefly discussed a few of them with the modules. We will consider their usage now.
Code cleanup and performance tuning in PHP scripts goes only so far to make pages fast enough. Caching engines prevent a trip to the server for pages that are already available. Caching can be done for internally compiled PHP scripts, the generated output or the intermediary data processing objects.
APC is an opcode caching engine and comes with PECL/PEAR repository. The compiled code from the PHP runtime engine is stored in the shared memory for later access. It can be linked into the PHP code or as Dynamic Shared Object (DSO) and by specifying the extension as apc.so in the php.ini file
eAccelerator is a similar compiled-state PHP 4 caching engine and also optimizes as well as encodes code. The resulting can be distributed to those that have eAccelerator installed. Again the compiled objects are stored in shared memory and the different setting such as memory size, cache directory, time-to-live, prune period can be described in the php.ini file. The extension entry is accelerator.so Similarly Zend optimizer uses the native Zend engine that powers PHP to cache compile time objects.
JPCache works by storing the generated output of a PHP script or disk to disk or in SQL Server. It's written as a PHP library. In addition to caching, it also provides compression resulting in more improvements in page load time. Configuration options include those for the database, the credentials and the compression level.
Memcached is a distributed memory object caching system and is available as a PHP DSO. we can add entries to memcache using the add method that takes key values as parameters.
The get_stats() method on the memcache is particularly helpful and gives such information as current connections, total connections, hits, misses, current items, total items, etc.
As we see now, there are overlap between the caching frameworks. The complimentary ones could increase performance but others may not work well together.
JPCache and memcached can work well with other but because eAccelerator and Zend have their own encoders, they are mutually exclusive. Moreover, you only want one opcode caching. Memcached is a great choice for large objects and varied lifetime or small objects but frequent database access. If there are static pages, JPCache works well. If there is a lot of PHP code, then an opcode caching like APC works well.
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