SoFunction
Updated on 2025-04-08

Nginx FastCGI cache implementation example

introduction

With the development of web applications and the continuous growth of traffic, how to improve application performance and reduce server load has become the focus of developers and system administrators. As a commonly used performance optimization method, FastCGI cache can significantly reduce requests to back-end servers and improve system response speed. As a high-performance reverse proxy server, Nginx provides powerful FastCGI caching support, making dynamic content caching more efficient and flexible.

1. The basic concept of FastCGI cache

FastCGI (Fast Common Gateway Interface) is an improved version of CGI (Common Gateway Interface) for handling dynamic requests. Unlike traditional CGI, FastCGI improves performance by keeping the application server's process pool, thus avoiding the overhead of creating and destroying processes every request. FastCGI enables web servers to communicate efficiently with backend applications (such as PHP, Python, etc.) and generate dynamic content.

FastCGI cache caches dynamic content generated through FastCGI to reduce requests to the backend application server. When the same request arrives again, Nginx will directly return the cached content without forwarding it to the backend application server, thereby increasing the response speed and reducing the burden on the backend application server.

2. How Nginx FastCGI cache works

Nginx's FastCGI cache is a file system-based cache. By configuring the cache area and cache storage directory, Nginx caches dynamic content generated by the backend application to disk and manages cached content based on the configured cache failure time and cleaning policies.

The basic workflow of FastCGI caching is as follows:

  • Client request reaches Nginx:The client initiates a request, and Nginx receives the request.
  • Check the cache:Nginx checks whether there is a cache based on the cache key (usually the requested URL or query string).
  • Cache hits:If there is corresponding content in the cache, Nginx will directly return the cached data to reduce communication with the backend application server.
  • Cache Missing:If there is no corresponding content in the cache, Nginx will forward the request to the backend application server, which will process the request and generate dynamic content.
  • Cache updates:After the dynamic content is returned, Nginx will store it in the cache for future requests.

3. Nginx FastCGI cache configuration

To enable FastCGI cache in Nginx, the following aspects need to be configured:

  • Configure cache storage area:useproxy_cache_pathorfastcgi_cache_pathThe instruction specifies the cached storage directory, cache area size and other parameters.
  • Enable FastCGI cache:usefastcgi_cacheThe directive enables FastCGI cache and specifies the cache area.
  • Set cache validity period:usefastcgi_cache_validThe command sets the valid time of cached content.
  • Control cache cleaning:usefastcgi_cache_use_staleandfastcgi_cache_min_usesSuch instructions to control the cache cleaning strategy.

Here is a detailed example of configuring FastCGI cache:

http {
    # Configure FastCGI cache storage path    fastcgi_cache_path /var/cache/nginx/fastcgi_cache levels=1:2 keys_zone=fastcgi_cache:10m inactive=60m max_size=1g;
    
    server {
        listen 80;
        server_name ;

        # Enable FastCGI cache        location / {
            fastcgi_cache fastcgi_cache;
            fastcgi_cache_valid 200 1h;    # 200 Response cache for status codes 1 hour            fastcgi_cache_valid 404 1m;    #404 Response cache of status code 1 minute            fastcgi_cache_use_stale error timeout updating;  # Use cache when backend timeout or error occurs            fastcgi_cache_min_uses 3;      # The request is cached only when the number of requests reaches more than 3 times.            fastcgi_pass 127.0.0.1:9000;  # Forward to PHP-FPM to process PHP requests            include fastcgi_params;
        }
    }
}

Configuration instructions:

  • fastcgi_cache_path: Specify the path to cache storage (/var/cache/nginx/fastcgi_cache), as well as the name of the cache area and other cache parameters (levels=1:2、keys_zone=fastcgi_cache:10mwait).
  • fastcgi_cache: Enable FastCGI cache and specify the cache area.
  • fastcgi_cache_valid: Set the cache validity period of different HTTP status codes.
  • fastcgi_cache_use_stale: Configure the cache to use when the cache timeout or when the backend server error occurs.
  • fastcgi_cache_min_uses: Set the minimum number of cache usage times to avoid infrequently accessed content being cached.

4. Advanced configuration and optimization of FastCGI cache

In addition to the basic FastCGI cache configuration, Nginx also provides a variety of instructions and configuration options for further optimizing cache performance and controlling cache behavior.

1. Cache key-value configuration

Nginx identifies each cache entry through a cache key. By default, the cache key is the requested URI, but the cache key can be customized as needed, such as generating a cache key based on a query string, a request header, or other parameters.

Configuration example:

location / {
    fastcgi_cache_key "$scheme$request_method$host$request_uri";
}

In this configuration, the cache key is by the protocol ($scheme), request method ($request_method), host ($host) and URI ($request_uri)composition. In this way, even if the URI is the same, but the request method or protocol is different, different content can be cached separately.

2. Expiration and cleaning strategies of cache

Nginx supports a variety of cache cleaning strategies to ensure that caches expire or do not occupy too much disk space. Commonly used cache expiration settings include:

  • inactive: Specifies the expiration time of the cache entry without request. The default value is 10 minutes.
  • max_size: Specify the maximum size of the cache area. When the cache directory reaches that size, Nginx cleanses up the oldest cache items.
  • keys_zone: Specify the size of the cache area, that is, the memory space size that stores the cache key and its data.

Configuration example:

fastcgi_cache_path /var/cache/nginx/fastcgi_cache levels=1:2 keys_zone=fastcgi_cache:10m inactive=30m max_size=2g;

In this configuration,inactive=30mIt means that the cache item will expire if it is not accessed within 30 minutes.max_size=2gIndicates that the maximum size of the cache area is 2 GB.

3. Dynamic interaction between cache and background applications

Nginx supports configurationfastcgi_cache_use_staleTo control whether expired cache is used in case of cache misses. Instead of returning a 500 error or other exception response, Nginx can return expired cached content when an error or timeout occurs on the backend application server.

Configuration example:

fastcgi_cache_use_stale error timeout invalid_header updating;

In this configuration, when an error, timeout, or invalid response header occurs in the backend application, Nginx will return expired cached content, avoiding the client waiting for a long time.

4. Cache control of dynamic content

Nginx supports controlling what content can be cached through request headers or other conditions. For example, you can useCache-ControlThe header controls whether to cache dynamic content, or determines whether to cache certain requests based on certain parameters in the request.

Configuration example:

location / {
    fastcgi_cache fastcgi_cache;
    fastcgi_cache_valid 200 1h;
    fastcgi_cache_bypass $cookie_session;  # If a session cookie exists, skip cache}

In this configuration,fastcgi_cache_bypassThe command will check the requestedsessionCookie. If the cookie exists, the cache will be skipped and the backend application will be directly accessed.

5. Application scenarios of FastCGI cache

Nginx's FastCGI cache can be widely used in many different types of web application scenarios, especially those that need to handle a large number of dynamic requests. Here are some typical application scenarios:

1. Performance optimization of high-traffic websites

For websites with high traffic, especially in scenarios where content updates frequently but does not require real-time calculations every time, FastCGI cache can significantly reduce the load on the backend application server. Nginx can cache dynamic page content and only regenerate caches when cache expires or content is updated, thereby greatly improving response speed.

2. API Cache

When building RESTful APIs or other web services, some API requests (such as queries, statistics, etc.) may return the same results. FastCGI cache can cache these results to reduce the pressure on backend database queries and improve API performance.

3. Reduce database access

When handling a large number of dynamic requests, Nginx can cache database query results to reduce the frequency of access to the database. For pages with large visits and fewer content updates, Nginx cache can significantly reduce database load and improve overall performance.

6. Performance optimization of Nginx FastCGI cache

  • Resize cache storage:Adjust according to cache usage frequency and storage needsfastcgi_cache_pathInmax_sizeandkeys_zoneParameters to optimize cache storage.
  • Reasonably set the cache expiration time:Set up reasonably according to the frequency of content updates and business needs.fastcgi_cache_validandinactiveParameters to ensure that the cache does not take up too much disk space and can provide sufficient cache hit rate.
  • Optimize cache cleaning strategy:Optimize cache cleaning strategies based on the server's disk space and cache hit rate to avoid excessive space occupied by cache invalid or expired content.
  • Allocate enough memory:Configure enough memory for Nginx to ensure the effectiveness of the cache area and avoid degradation in cache performance due to insufficient memory.

7. Summary

Nginx's FastCGI caching is an effective way to improve web application performance and reduce the burden on backend servers. By reasonably configuring cache storage, cache expiration time and cache cleaning strategies, the processing process of dynamic content can be significantly optimized and the user experience can be improved.

This is the end of this article about the implementation example of Nginx FastCGI cache. For more information about Nginx FastCGI cache, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!