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Alternative PHP Cache

This article describes about Alternative PHP Cache (APC) to improve PHP application performance. In PHP scripting program, two types of caching technique are used. One is opcode cache and the second one is data cache. The APC is opcode cache type, which would significantly speed up your applications. It caches both user variables and PHP code so that it minimizes overall server load and memory usage.

APC can be explained further as following; if a site has thousands of requests per second to improve the performance of the application APC would be implemented. APC caches the compiled output of each PHP script and reuse it for subsequent requests. APC is a free, open and robust framework for caching and optimizing PHP intermediate code.

How it improves performance of the applications?

APC utilizes shared memory for read/write operations; it stores the opcode in shared memory then copies opcode into execution process, whenever required. Classes and functions are also stored in shared memory. APC also provides a user cache for storing application data.

In APC technique for every new data request, system checks the data availability in cache. If the data is not available, it would be stored and executed from source directory and then stored in cache for future reference. APC cache has predefined methods available for developers to store and fetch data. APC allows you to cache arrays, objects, functions and references.

Configuration is an important factor in APC; it requires few steps to be followed for proper configuration. It takes time to configure and would be re-configured whenever PHP script is added. Two things to note down are: First, ensure how much memory is going to be allocated to APC and second, check whether APC looks at files which have been modified for every request. You can view APC statistics through browser by running apc.php script, it can be placed in your web directory. If the cache capacity reached maximum it has to be forcefully clean. Data capacity should be minimized in a well configured cache. By default APC uses 32Mb. So use APC for caching page of site which does not change often.

If APC is built with Memory Mapping, it will use only one memory segment, unlike when APC is build with SHM (Shared Memory), it will support multiple memory segment. A well configured APC will absolutely speed up the application. Use APC caching module depends on project requirements which are not change often and will not grow large. If you want to develop the high-traffic website with scalability using PHP, you’ve come to the right place. PHP web developers at Innoppl have experience developing high-traffic websites and we know what it takes.