Consumer Priority

What is consumer priority?

When consumers connected to LavinMQ have different priorities, messages are delivered first to those with higher priority and available capacity. Lower-priority consumers receive messages only when higher-priority ones are blocked.

When to use consumer priority?

A typical scenario where consumer priority proves beneficial is resource management. Assign higher priorities to consumers with greater computing power or available resources, enabling efficient handling of critical tasks.

Assign priority to a consumer by setting the x-priority argument in the basic.consume method to an integer value. If no value is specified, the priority is 0. Higher numbers indicate higher priority, with both positive and negative numbers available.

Example: Set the priority on a consumer to 10

import pika

connection = pika.BlockingConnection(pika.URLParameters('host-url'))
channel = connection.channel()

def callback(ch, method, properties, msg):
		print(f"[✅]  { msg }")
		ch.basic_ack(delivery_tag=method.delivery_tag)

channel.basic_consume(
    "test_queue",
    callback,
    auto_ack=False,
    arguments**=**{
      'x-priority':10
    }
)
connection.close()

Consumer capacity

A consumer has capacity when ready to receive a message. It becomes blocked when it can’t, such as when the prefetch limit of unacknowledged messages is reached.
A consumer is either ready or blocked at any given moment.

Multiple consumers with the same priority

If multiple consumers share the same priority, LavinMQ sends messages to the first consumer bound to the queue by default, rather than using a round-robin approach. To ensure fair message distribution among same-priority consumers, set the prefetch value to 1.

Single active consumers and priority consumers

When the single active consumer feature is enabled, priority consumers cannot be used on that queue.

Introduction

Configuration

Language Support

AMQP 0-9-1 Overview

More Exchange Types

More Consumer Features

Queue Deep-dive

Other Features

Reliable Message Delivery

High Availability

Monitoring

Management HTTP API

Tutorials

Networking

LavinMQ CLI