What is process cache in php? How to achieve it?

PHP (Hypertext Preprocessor) is an open source server scripting language mainly used for website development. As website traffic increases, PHP pages will load more slowly, reducing user experience. In order to improve the loading speed of PHP pages, you can use process caching technology. This article will introduce how to use PHP to implement process caching.

1. What is process caching

Process caching refers to caching operations or data repeated in multiple requests into memory, avoiding multiple access to the database or File system overhead, thereby improving system operating efficiency. In PHP, process caching can be implemented using extensions such as APC (Alternative PHP Cache) or Memcache.

2. Use APC to implement process caching

APC is a process caching extension that comes with PHP. It stores PHP compiled code and data in shared memory. , avoiding the overhead of recompiling for each request. The following is an example of using APC to implement caching:

//检查是否有缓存
if($data = apc_fetch('cached_data')){
  echo 'Data from APC:';
  print_r($data);
}
else {
  //没有缓存，从数据库中获取数据
  $data = get_data_from_database();
  //存储到APC缓存中
  apc_store('cached_data', $data, 3600);
  //输出数据
  echo 'Data from DB:';
  print_r($data);
}

In the above code, first check whether there is data in the APC cache. If there is, the data is read from the cache and printed, otherwise the data is obtained from the database and stored in the APC cache, and then the data is output.

3. Use Memcache to implement process caching

Memcache is a distributed memory object caching system that can share cached data among multiple servers. By storing duplicate data in memory, the overhead of each database access is avoided. The following is an example of using Memcache to implement caching:

//连接到Memcache服务器
$memcache = new Memcache;
$memcache->connect('localhost', 11211);

//检查是否有缓存
if($data = $memcache->get('cached_data')){
  echo 'Data from Memcache:';
  print_r($data);
}
else {
  //没有缓存，从数据库中获取数据
  $data = get_data_from_database();
  //存储到Memcache缓存中
  $memcache->set('cached_data', $data, 0, 3600);
  //输出数据
  echo 'Data from DB:';
  print_r($data);
}

In the above code, first connect to the Memcache server, and then check whether the cache exists. If it exists, read the data from the cache and print it, otherwise get the data from the database, store it in the Memcache cache, and then output the data.

4. Notes

1. Process caching is only applicable to reusable data, such as configuration files, template files, etc., and is not applicable to dynamically generated data data. If the cached data changes frequently, the cache will no longer be effective.
2. When using process cache, you need to pay attention to the cache setting time. If the setting time is too long, the cache data will not be updated in time. If the setting time is too short, the cache will be updated frequently.
3. When using process cache, you need to avoid the problem of low cache hit rate. You can improve the cache hit rate by optimizing SQL statements, using cache tags, etc.

Conclusion

This article introduces how to use PHP to implement process caching technology to improve the operating efficiency of the system. Whether it is APC or Memcache, you need to pay attention to the cache time and hit rate during use to give full play to the role of the cache.

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