How to implement load balancing and overload protection of services in microservice architecture?

With the development of Internet technology and the continuous expansion of application scenarios, microservice architecture has become a trend in Internet application development. The microservice architecture can split a large application system into multiple small services. Each service can be independently deployed, maintained, and expanded independently, thus improving the scalability and maintainability of the application system, improving development efficiency and Operation and maintenance efficiency.

However, in the microservice architecture, the communication protocol between services is carried out through the network, and the communication quality of the network is very unstable. If the request volume of a certain service is too large under high load conditions, it may cause the service to crash or the response time to become longer, affecting the performance of the entire application system. Therefore, how to achieve high-availability service load balancing and overload protection is a major challenge in microservice architecture.

This article will introduce how to implement service load balancing and overload protection in microservice architecture from the following aspects.

1. Service load balancing

Service load balancing refers to the balanced distribution of requests to multiple service nodes to achieve the purpose of balancing the load. Common load balancing algorithms include polling, weighted polling, least connections, shortest response time, etc. In a microservice architecture, service gateways are generally used to implement load balancing of services.

1. Service Gateway

The service gateway is an important component in the microservice architecture and is responsible for service routing and load balancing. The service gateway can route requests from clients to different back-end services and select service nodes according to a certain load balancing algorithm.

2. Load balancing algorithm

In the service gateway, achieving load balancing of services requires selecting an appropriate algorithm. Common algorithms include polling, weighted polling, minimum number of connections, minimum response time, etc. The polling algorithm refers to distributing requests to different service nodes in sequence, and each node shares the load equally, but it cannot handle the uneven load of the nodes. The weighted polling algorithm can assign different weights to different service nodes to achieve proportional allocation of requests to service nodes. The minimum number of connections algorithm refers to sending requests to the service node with the smallest number of current connections to achieve load balancing and flow control. The shortest response time algorithm refers to sending requests to the service node with the shortest response time. However, this algorithm may lead to uneven node load and needs to be adjusted in conjunction with the flow control strategy.

2. Overload protection

In the microservice architecture, since the communication between nodes is carried out through the network, the communication quality of the network is unstable. If the request volume of a certain service node is too large, it may cause the node to be overloaded or even crash, affecting the stability of the entire system. Therefore, it is necessary to implement an overload protection mechanism to protect the stability of service nodes.

1. Flow control

Flow control refers to setting the number of concurrent requests for a node. When the number of concurrent requests for a node reaches the threshold, new requests are rejected. Flow control can protect nodes from being overwhelmed by requests and enable nodes to respond to requests normally. Common flow control algorithms include token bucket algorithm, leaky bucket algorithm, window counter, etc.

2. Meltdown

Meltdown means that when an exception occurs on a service node, the node's request is immediately disconnected to prevent requests from continuing to be sent to the abnormal node and reduce the node's response speed. Circuit breakers can reduce abnormal requests from nodes and ensure node stability and availability. Common fusing algorithms include state machine-based fusing algorithms, time window-based fusing algorithms, etc.

3. Downgrade

Downgrade refers to reducing the service quality and achieving the minimum function of the service when the node is overloaded or abnormal. Downgrading can ensure the stability of the node and the availability of the service. Common downgrade solutions include downgrade services, downgrade parameters, downgrade return values, etc.

Summary

In the microservice architecture, service load balancing and overload protection are important means to achieve high availability. Through reasonable load balancing algorithms and overload protection mechanisms, the stability and availability of service nodes can be guaranteed and the performance and reliability of the system can be improved.

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