synckit

Perform async work synchronously in Node.js using worker_threads with first-class TypeScript and Yarn P'n'P support.

Usage

Install

# yarn
yarn add synckit

# npm
npm i synckit

API

// runner.js
import { createSyncFn } from 'synckit'

// the worker path must be absolute
const syncFn = createSyncFn(require.resolve('./worker'), {
  tsRunner: 'tsx', // optional, can be `'ts-node' | 'esbuild-register' | 'esbuild-runner' | 'tsx'`
})

// do whatever you want, you will get the result synchronously!
const result = syncFn(...args)

// worker.js
import { runAsWorker } from 'synckit'

runAsWorker(async (...args) => {
  // do expensive work
  return result
})

You must make sure, the result is serializable by Structured Clone Algorithm

Types

export interface GlobalShim {
  moduleName: string
  /**
   * `undefined` means side effect only
   */
  globalName?: string
  /**
   * 1. `undefined` or empty string means `default`, for example:
   * ```js
   * import globalName from 'module-name'
   * ```
   *
   * 2. `null` means namespaced, for example:
   * ```js
   * import * as globalName from 'module-name'
   * ```
   *
   */
  named?: string | null
  /**
   * If not `false`, the shim will only be applied when the original `globalName` unavailable,
   * for example you may only want polyfill `globalThis.fetch` when it's unavailable natively:
   * ```js
   * import fetch from 'node-fetch'
   *
   * if (!globalThis.fetch) {
   *   globalThis.fetch = fetch
   * }
   * ```
   */
  conditional?: boolean
}

Options

execArgv same as env SYNCKIT_EXEC_ARGV
globalShims: Similar like env SYNCKIT_GLOBAL_SHIMS but much more flexible which can be a GlobalShim Array, see GlobalShim's definition for more details
timeout same as env SYNCKIT_TIMEOUT
transferList: Please refer Node.js worker_threads documentation
tsRunner same as env SYNCKIT_TS_RUNNER

Envs

SYNCKIT_EXEC_ARGV: List of node CLI options passed to the worker, split with comma ,. (default as []), see also node docs
SYNCKIT_GLOBAL_SHIMS: Whether to enable the default DEFAULT_GLOBAL_SHIMS_PRESET as globalShims
SYNCKIT_TIMEOUT: timeout for performing the async job (no default)
SYNCKIT_TS_RUNNER: Which TypeScript runner to be used, it could be very useful for development, could be 'ts-node' | 'esbuild-register' | 'esbuild-runner' | 'swc' | 'tsx', 'ts-node' is used by default, make sure you have installed them already

TypeScript

`ts-node`

If you want to use ts-node for worker file (a .ts file), it is supported out of box!

If you want to use a custom tsconfig as project instead of default tsconfig.json, use TS_NODE_PROJECT env. Please view ts-node for more details.

If you want to integrate with tsconfig-paths, please view ts-node for more details.

`esbuild-register`

Please view esbuild-register for its document

`esbuild-runner`

Please view esbuild-runner for its document

`swc`

Please view @swc-node/register for its document

`tsx`

Please view tsx for its document

Benchmark

It is about 50x faster than sync-threads but 10x slower than native for reading the file content itself 1000 times during runtime, and 40x faster than sync-threads but 10x slower than native for total time on my personal MacBook Pro with 64G M1 Max.

And it's almost 5x faster than deasync but requires no native bindings or node-gyp.

See benchmark.cjs and benchmark.esm for more details.

You can try it with running yarn benchmark by yourself. Here is the benchmark source code.