Ractor Map

Use ractor_map for ordered CPU-bound mapping in worker Ractors.

The mapper must be shareable. A common approach is Ractor.shareable_proc.

ruby

require "digest"
require "fiber_stream"

records = [
  { name: "alpha.bin", payload: +"A" * 200_000 },
  { name: "bravo.bin", payload: +"B" * 120_000 }
]

hash_record =
  Ractor.shareable_proc do |record|
    payload = record.fetch(:payload)

    {
      name: record.fetch(:name),
      bytes: payload.bytesize,
      sha256: Digest::SHA256.hexdigest(payload)
    }
  end

digests =
  FiberStream::Source.each(records)
    .ractor_map(workers: 2, input_transfer: :move, &hash_record)
    .run_with(FiberStream::Sink.to_a)

Results are emitted in input order. At most workers upstream elements are pulled but not yet emitted.

Use input_transfer: :move only when the sender will not use the moved object again.

The runnable version is examples/ractor_map_hashing.rb.

Ractor Map ​

Ractor Map