Active Job Async adapter
The Async adapter runs jobs with an in-process thread pool.
This is the default queue adapter. It's well-suited for dev/test since it doesn't need an external infrastructure, but it's a poor fit for production since it drops pending jobs on restart.
To use this adapter, set queue adapter to
config.active_job.queue_adapter = :async
To configure the adapter's thread pool, instantiate the adapter and pass your own config:
config.active_job.queue_adapter = ActiveJob::QueueAdapters::AsyncAdapter.new \ min_threads: 1, max_threads: 2 * Concurrent.processor_count, idletime: 600.seconds
The adapter uses a Concurrent Ruby thread pool to schedule and execute jobs. Since jobs share a single thread pool, long-running jobs will block short-lived jobs. Fine for dev/test; bad for production.