How to Increase the Availability of an Application with RabbitMQ?


If you have used RabbitMQ for managing the messaging part of your applications, then you are certainly aware of the configuration issues which are recurrent with it. Software engineering experts who have used RabbitMQ for an extended period of time know that it can face certain configuration errors.

Therefore, it is necessary to configure it correctly. In this way, you can achieve the best possible performance along with getting the cluster which is the most stable of them all. This article focuses on a number of tips and techniques which can improve the availability and uptime of your application.

Limit Queue Size

The arrangement of queues matters in the RabbitMQ environment. If you wish to attain maximum performance for your application then ensure that these queues remain shorter in size. When a queue is considerably large in size, then the accompanied processing overhead slows down the performance of the application. In order to achieve optimal performance for your application, queues should remain close to 0.

Turn On Lazy Queues

Since RabbitMQ 3.6, there is an option in the messaging platform to use lazy queues. In lazy queues, messages are automatically redirected to the secondary memory of your disk and are then stored there. When the need arises for a message, then the main memory calls out the corresponding message from the disk. Since all the messages are stored on the disk, therefore it helps to manage and optimize the usage of RAM. On the other hand, it also promises additional time for the throughput.

The use of lazy queues ensures you can produce improved stable clusters. These cluster features are known to infuse a certain degree of predictability in the performance. As a result, the server’s availability gets a much-needed boost. If your application involves too much processing of batch jobs and deals with a high number of messages, then you might be concerned that the speed of publisher may not always be kept up by the consumers. In this case, you must give a thought to turn off the lazy queues.

Manage Cluster Setup

The node collection in RabbitMQ is also known as a cluster. In order to improve availability, make sure that the clients are facilitated with data replication in the event of any possible or expected failure. This means that even if a cluster is disconnected, clients could access it to fulfill their requirements.

In Cloud AMQP, you can create 3 clusters. You have to locate all nodes for various availability zones (AWS) while queues should be replicated (HA) amongst the availability zones.

If a node goes down, then there should be a mechanism which can transfer processing to the remaining cluster nodes for keeping up the availability of the application. To do this, you can use a load balancer with the instances of the RabbitMQ. The load balancer can help with the message publishers for transparent brokers distribution.

Keep in mind that in Cloud AMPQ, 60 seconds is the max failover time. The DNS TTL runs every 30 seconds while the endpoint health is processed after every 30 seconds.

By default, message queues are positioned on a single node. However, they can be reached and seen by all the other nodes. For replication of queues in the node cluster, you can visit this link to achieve high availability. If you need more information on the configuration of nodes in your cluster, then you can visit this link.

Using Durable Queues and Persistent Messages

If it is absolutely critical that your application cannot lose a message, then you can configure your queues as “durable”. In this way, your sent messages are now delivered with a “persistent” mode. If you wish to prevent the loss of messages with the broker, then you have to consider broker crashes, broker hardware failure, and broker restart issues. In order to make sure that the broker definitions and messages are not hampered by restarts, you can store them on the disk. Queues, exchanges, and messages which are not declared as persistent and durable are missed if the broker restarts.

Using the Federation for the Cloud

According to some experts, clustering between regions or cloud is not recommended. This means you do not have to think about the distribution of nodes across data centers or regions. In case, an entire cloud region is disconnected, the impact can force the CloudAMQP to falter as well, though it not necessary that it will be affected. The nodes in the cluster are distributed among availability zones in the same region.

If you wish to safeguard the setup when a complete region goes down, then you can configure two clusters for separate regions and apply “federation” between them. Federation is a plugin in RabbitMQ. The use of the federation plugin allows your application to leverage more than one broker which are spread across separate systems.

Turn Off HiPE

If you plan to use HiPE, then avoid it. When HiPE is used, the server throughput is noticeably increased but it also increases the startup time. If HiPE is turned on, then the compilation of RabbitMQ is triggered at the startup. This also means that the startup time can increase to as much as 3 minutes. As a consequence, you might face issues during a server restart.

Disable Detailed Mode

If you have set the RabbitMQ Management statistics rate mode as “detailed, disable it immediately. When this mode is enabled, it can affect the performance and availability of the application. As such, it should not be utilized in production.

Limit Priority Queues

All the priority levels work on the Erlang VM with an internal queue. This queue consumes the considerable resource. For general use, you may not need more than 5 priority levels.

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