Parallel

Crystal library for parallel processing using Fiber::ExecutionContext.

Requirements

• Crystal 1.6.0+
• Compile flags: -Dpreview_mt -Dexecution_context

Installation

Add to shard.yml:

dependencies:
  parallel:
    github: kojix2/parallel

Run shards install

Usage

require "parallel"

# Parallel map
[1, 2, 3, 4].par_map { |x| x * 2 }
# => [2, 4, 6, 8]

# Parallel each
[1, 2, 3, 4].par_each { |x| puts x }

# Chunk processing (fewer context switches)
[1, 2, 3, 4].par_map(chunk: 2) { |x| x * 2 }
# => [2, 4, 6, 8] (same result, better performance)

# Custom ExecutionContext
context = Fiber::ExecutionContext::MultiThreaded.new("workers", 8)
[1, 2, 3, 4].par_map(context) { |x| x * 2 }

Compilation

crystal build -Dpreview_mt -Dexecution_context your_app.cr
crystal spec -Dpreview_mt -Dexecution_context

Methods

• par_map(execution_context = nil, *, chunk = nil, &block)

  • Applies block to each element in parallel, returns array of results.
  • chunk: Process elements in chunks to reduce context switches.

• par_each(execution_context = nil, *, chunk = nil, &block)

  • Applies block to each element in parallel for side effects.
  • chunk: Process elements in chunks to reduce context switches.

Notes

• Works with any Enumerable (Array, Range, Set, Hash, etc.)
• Indexable types (Array, Slice) preserve order
• Exceptions are propagated from parallel tasks
• Uses global ExecutionContext by default for performance
• Thread safety is your responsibility when accessing shared resources

Contributing

• Fork this repository
• Report bugs
• Fix bugs and submit pull requests
• Write, clarify, or fix documentation
• Suggest or add new features

License

MIT

This library contains code generated by AI.