Nodejs sets the maximum number of received requests

nodejs is an open source back-end JavaScript runtime environment based on event-driven and non-blocking I/O. The unique non-blocking I/O mode of nodejs enables it to handle a large number of concurrent connections and has excellent performance.

However, nodejs' default maximum request limit can become an issue when handling a large number of requests. In this article, we will take a deep dive into how to set the maximum number of received requests in nodejs and improve the performance and reliability of your application.

1. nodejs default maximum request limit

In nodejs, the http.Server object is responsible for accepting and processing received HTTP requests. The http.Server object sets a default maximum request limit when it is started, which is the number of client requests that can be processed simultaneously. If the maximum request limit is exceeded, the request will be rejected. By default, the maximum number of requests for nodejs is 2^16 or about 64K. This means that if 64K users try to connect to your application at the same time, most of those requests will be rejected. This will severely impact your application's performance and reliability.

2. How to set the maximum request limit

To set the maximum request limit for nodejs, you need to change the maxConnections property of the http.Server object. This property sets the maximum number of client requests. The default value for this property is Infinity, which means no limit. You can choose an appropriate number to set the maximum number of connections to avoid request rejection issues. Here is the sample code on how to change the maximum number of connections:

const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello World!');
});

server.maxConnections = 10000; // 设置最大连接数为 10000

server.listen(8080);

In the above example, we set the maximum number of connections to 10000. This means that up to 10,000 clients can be connected simultaneously. When the number of client connections exceeds this limit, they are placed in a waiting queue until an idle connection becomes available.

Please note that setting maxConnections does not immediately give your application better performance. This is just a limitation, and your server hardware (CPU, memory, network bandwidth, etc.) may still become a performance bottleneck. Therefore, you need to make trade-offs and balances between hardware and application configuration.

3. How to test the maximum request limit

To test the maximum request limit of nodejs, use a concurrent request testing tool such as ApacheBench or Siege. These tools can generate large numbers of simulated client requests to test your server's performance and stability under heavy load.

The following is an example of benchmarking using ApacheBench. We will send 100000 requests, using concurrent connections in 10 seconds:

ab -n 100000 -c 10000 -k http://localhost:8080/

In the above command, the -n option indicates the number of requests sent, the -c option indicates the number of concurrent connections, and the -k option indicates the use Keep-Alive to optimize connection reuse. You can modify and adjust it to suit your needs.

4. How to optimize performance and reliability

In addition to setting a maximum request limit, you can take other steps to improve the performance and reliability of your nodejs application. Here are some helpful tips and tricks:

• Compress response content: Use a compression format like gzip or deflate to compress response content to reduce network bandwidth and page load time.
• Use caching: Enable appropriate browser caching or server-side caching to reduce duplicate requests.
• Configuring DNS: The process of resolving domain names into IP addresses can become a performance bottleneck. Using a fast and reliable DNS server for your applications can greatly improve performance.
• Adjust hardware: Upgrade server hardware (CPU, memory, hard disk, and network interface) to handle more concurrent connections or data traffic.
• Use a load balancer: Use a load balancer to distribute traffic to improve reliability and scalability.
• Optimize code: Use performance tools to analyze and tune JavaScript code to maximize performance and reliability.

Summary

Setting the maximum request limit for nodejs can improve the performance and reliability of your application, especially when handling a large number of requests. Set the maxConnections property, increase the server hardware configuration, and use the concurrent request testing tool to test and optimize performance. Combining these tips, you can maximize the performance and reliability of your nodejs applications and provide a better experience for your users.

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