72 lines
2.0 KiB
Markdown
72 lines
2.0 KiB
Markdown
through2-concurrent
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===================
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[](https://nodei.co/npm/through2-concurrent/)
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A simple way to create a Node.JS Transform stream which processes in
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parallel. You can limit the concurrency (default is 16) and order is
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*not* preserved (so chunks/objects can end up in a different order to
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the order they started in if the transform functions take different
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amounts of time).
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Built using [through2](https://github.com/rvagg/through2) and has the
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same API with the addition of a `maxConcurrency` option.
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Non-`objectMode` streams are supported for completeness but I'm not
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sure they'd be useful for anything.
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Written by Thomas Parslow
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([almostobsolete.net](http://almostobsolete.net) and
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[tomparslow.co.uk](http://tomparslow.co.uk)) as part of Active Inbox
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([activeinboxhq.com](http://activeinboxhq.com/)).
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[](https://travis-ci.org/almost/through2-concurrent)
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Install
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-------
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```bash
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npm install --save through2-concurrent
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```
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Examples
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--------
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Process lines from a CSV in paralel. The order the results end up in
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the `all` variable is not deterministic.
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```javascript
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var through2Concurrent = require('through2-concurrent');
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var all = [];
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fs.createReadStream('data.csv')
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.pipe(csv2())
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.pipe(through2Concurrent.obj(
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{maxConcurrency: 10},
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function (chunk, enc, callback) {
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var self = this;
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someThingAsync(chunk, function (newChunk) {
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self.push(newChunk);
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callback();
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});
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}))
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.on('data', function (data) {
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all.push(data)
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})
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.on('end', function () {
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doSomethingSpecial(all)
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})
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```
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Contributing
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------------
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Fixed or improved stuff? Great! Send me a pull request [through GitHub](http://github.com/almost/through2-concurrent)
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or get in touch on Twitter [@almostobsolete][#tom-twitter] or email at tom@almostobsolete.net
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[#tom]: http://www.almostobsolete.net
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[#tom-twitter]: https://twitter.com/almostobsolete
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