---
title: Rails Solid Queue async mode
url: https://calvin.my/posts/rails-solid-queue-async-mode
published: 2026-01-07
updated: 2026-09-16
category: Operations
tags:
- Rails
- Solid Queue
- Ruby
- Job
summary: Solid Queue version 1.3.0 restores async mode, which runs the supervisor, worker, dispatcher, and scheduler within one process rather than separate processes. This design aims to reduce memory consumption and improve suitability for constrained deployment environments. The post explains enabling the mode through the job startup configuration and verifying it by checking whether the supervisor is identified as running in async rather than fork mode.
---

# Rails Solid Queue async mode

[Solid Queue](https://github.com/rails/solid_queue) brought back the Async Mode in its recent release. The mode runs all Solid Queue entities (Supervisor, Worker, Dispatcher, Scheduler) in the same process, with the intention of reducing its memory usage. This makes its deployment in resource-constrained environments friendlier.

* * *

## Setup

1. Update the solid queue gem to v1.3.0 or above.

2. We need to include a new flag `--mode=aync` to enable this feature. In this example, we are using supervisor, and this can be done by updating the command.

   ```bash
   [program:my-app-solid-queue]
   ...
   directory=/path/to/app/current
   command=/path/to/bundle exec ./bin/jobs start --mode=async
   environment=RAILS_ENV=production
   ...
   ```

3. Then we can reread and update the supervisor. 

* * *

## Validate

1. You can validate the current mode by checking the Solid Queue supervisor's name.

   ```bash
   # async
   user   1565540  solid-queue-async-supervisor(1.3.0): supervising 17576, 17584, 17592
   
   # fork
   user    431740 solid-queue-fork-supervisor(1.3.0): supervising 431785, 431789, 431793
   user    431785 solid-queue-dispatcher(1.3.0): dispatching every 1 seconds
   user    431789 solid-queue-worker(1.3.0): waiting for jobs in *
   user    431793 solid-queue-scheduler(1.3.0): scheduling some_jobs
   ```