Queue-Based Load Leveling Pattern
High load is our goal 😁. In case you agree read about Queue-Based Load Leveling Pattern. It helps to manage and distribute workloads efficiently. Don’t miss out — read till the end!
Read more about similar patterns:
- Inbox Pattern
- Queue-Based Load Leveling Pattern
Meanwhile, let’s begin.
Problem
It is common for the application to receive HTTP requests from other services.
However, at some point, the server may be overloaded and not able to process them all.
It leads to server slowness, unavailability, requests, and data loss.
Solution
Rather than sending requests directly to the server, other applications should place them in a queue.
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Later, the server can pull messages from that queue.
As you can see, it converts the push-based model into the pull one.
Pros & Cons
The obvious advantages are:
- the queue-based load leveling pattern ensures that a request/message was received successfully in case the server is down
- it increases server availability because handling requests no longer requires significant computational power
- stored request can be processed by a different server, releasing the load from the main one. The server that processes messages can scale separately
- stored requests can be retried upon failure until completion
- the server can balance its own load
Still, there are some drawbacks:
- it leads to eventual consistency
- messages or tasks held in a table require memory and storage
- this pattern requires an additional component that acts as a buffer between a task and a service it invokes (e.g. queue)
Similar patterns
This pattern is similar to the Inbox pattern. However, they solve different problems.
The Queue-Based Load Leveling pattern is more about load management, whereas the Inbox pattern emphasizes message consistency and delivery guarantee.
Here, the queue is a separate architecture component, that other services are aware of, while in the Inbox pattern, the queue is an implementation detail of the server itself.
Summary
The Queue-Based Load Leveling Pattern is particularly valuable in scenarios where high volumes of tasks need to be handled without overloading system resources or blocking user interactions.
It works by storing heave operations in an “inbox” table. Messages are then later processed when the service is less loaded.
Despite having drawbacks, the Inbox Pattern is highly useful in many scenarios, especially for applications that prioritize asynchronous handling over immediate task execution.
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