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- # throat
-
- Throttle the parallelism of an asynchronous, promise returning, function / functions. This has special utility when you set the concurrency to `1`. That way you get a mutually exclusive lock.
-
- [](https://travis-ci.org/ForbesLindesay/throat)
- [](https://coveralls.io/r/ForbesLindesay/throat?branch=master)
- [](https://david-dm.org/ForbesLindesay/throat)
- [](https://www.npmjs.com/package/throat)
- [](https://greenkeeper.io/)
-
- [](https://saucelabs.com/u/throat)
-
- ## Installation
-
- npm install throat
-
- ## API
-
- ### throat(concurrency)
-
- This returns a function that acts a bit like a lock (exactly as a lock if concurrency is 1).
-
- Example, only 2 of the following functions will execute at any one time:
-
- ```js
- const throat = require('throat')(2);
- // alternatively provide your own promise implementation
- const throat = require('throat')(require('promise'))(2);
- const promise = Promise.resolve();
-
- const resA = throat(() => /* async stuff... */ promise);
- const resB = throat(() => /* async stuff... */ promise);
- const resC = throat(() => /* async stuff... */ promise);
- const resD = throat(() => /* async stuff... */ promise);
- const resE = throat(() => /* async stuff... */ promise);
- ```
-
- ### throat(concurrency, worker)
-
- This returns a function that is an exact copy of `worker` except that it will only execute up to `concurrency` times in parallel before further requests are queued:
-
- ```js
- const throat = require('throat');
- // alternatively provide your own promise implementation
- const throat = require('throat')(require('promise'));
-
- const input = ['fileA.txt', 'fileB.txt', 'fileC.txt', 'fileD.txt'];
- const data = Promise.all(input.map(throat(2, fileName => readFile(fileName))));
- ```
-
- Only 2 files will be read at a time, sometimes limiting parallelism in this way can improve scalability.
-
- ## License
-
- MIT
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