Sidekiq 7: Rate limiting with capsules

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Sidekiq 7 adds a new feature called capsules Show snapshot .

Use cases:

  • a chrome queue limited to 1 for e.g. PDF processing to not overload the application server
  • an api queue, that limits a queue to 2 to protect the API server from too many requests in parallel


Sidekiq.configure_server do |config|
  # Edits the default capsule
  config.queues = %w[critical default low]
  config.concurrency = 5

  # Define a new capsule which processes jobs from the `unsafe` queue one at a time
  config.capsule("unsafe") do |cap|
    cap.concurrency = 1
    cap.queues = %w[unsafe]

Some notes:

  • To know the total threads per sidekiq server your need to sum up the concurrencies. In the example above this would be 6 threads in total. Instead of config.concurrency = 5 you also might have this config in a sidekiq.yml file saying :concurrency: 5.
  • In case you run multiple sidekiq servers (processes), the total number of concurrent capsules differs. In the example above with e.g. two application servers with a sidekiq role the maximum number of jobs in the unsafe queue is 2. And the total number of threads 12.
  • The queues configured for a capsule are still accessible for all other jobs. In the example above it is possible to run 6 jobs in the critical queue. The order of the jobs is configured with the priority for each queue.
Last edit
Daniel Straßner
Source code in this card is licensed under the MIT License.
Posted by Emanuel to makandra dev (2023-05-22 10:06)