https://github.com/danvk/async-iteration

Experiments with async iterators
https://github.com/danvk/async-iteration

Last synced: 10 months ago
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Experiments with async iterators

• Host: GitHub
• URL: https://github.com/danvk/async-iteration
• Owner: danvk
• Created: 2017-08-22T17:35:05.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2023-09-27T20:43:09.000Z (almost 3 years ago)
• Last Synced: 2025-01-03T03:50:13.525Z (over 1 year ago)
• Language: TypeScript
• Size: 3.91 MB
• Stars: 3
• Watchers: 3
• Forks: 3
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

          
# Async Iteration Playground

See [my post][1] about [async iterators][2] on Medium from 2017. Things have gotten considerably better in Node land since that post was written.

## Quickstart

    yarn

    ./node_modules/.bin/ts-node async-iter.ts

    python line_reader.py

    python csv_reader.py

## Results (2023)

Play around with your node version and `target` in `tsconfig.json` to see how this is getting better.

With Node 18.8.0:

```

$ ts-node async-iter.ts

range sync: 8 ms

range async: 54 ms

lines async: 117 ms

lines async chunked: 43 ms

lines sync: 58 ms

```

With Node 16.19.1:

```

$ ts-node async-iter.ts

range sync: 8 ms

range async: 56 ms

lines async: 132 ms

lines async chunked: 46 ms

lines sync: 62 ms

```

Now on a 2022 M2 MacBook Air with node 14.17.1, TypeScript 3.9 and `"target": "esnext"`:

```

$ ts-node async-iter.ts

range sync: 19 ms

range async: 62 ms

lines async: 154 ms

lines async chunked: 78 ms

lines sync: 96 ms

```

Compare with Python 3.11.4:

```

$ python line_reader.py

Read 549996 lines, 32871385 bytes in 0.099241 s

$ python csv_reader.py

Read 549996 lines, 4949964 cells in 0.349307 s

```

So in 2023, Python 3.11 and Node 18.8 are within about 20% of one another (117ms for "range async" in Node vs. 99ms for Python).

### Older Results (2017–2020)

With node 14.2.0, TypeScript 3.9 and `"target": "esnext"`:

```

$ ts-node async-iter.ts

range sync: 21 ms

range async: 125 ms

lines async: 299 ms

lines async chunked: 132 ms

lines sync: 169 ms

```

With node 12.16.2, TypeScript 3.9 and `"target": "esnext"`:

```

$ ts-node async-iter.ts

range sync: 31 ms

range async: 136 ms

lines async: 338 ms

lines async chunked: 197 ms

lines sync: 184 ms

```

With node 10.1.0, TypeScript 2.8 and `"target": "esnext"`:

```

$ ./node_modules/.bin/ts-node async-iter.ts

range sync: 30 ms

range async: 172 ms

lines async: 621 ms

lines async chunked: 283 ms

lines sync: 358 ms

```

vs. node 8.11.2 and `"target": "es6"`:

```

$ ./node_modules/.bin/ts-node async-iter.ts

range sync: 30 ms

range async: 1408 ms

lines async: 1800 ms

lines async chunked: 236 ms

lines sync: 370 ms

```

So the simplest `for await of` loop has gotten ~8x faster and the async csv

parser has gotten ~3x faster.

For comparison, Python 3.6.5 reads the same file in 145ms:

```

$ python3.6 line_reader.py

Read 549996 lines, 32871385 bytes in 0.295456 s

$ python3.7 csv_reader.py

Read 549996 lines, 4949964 cells in 0.936364 s

```

[1]: https://medium.com/p/4767df03d85b/

[2]: https://github.com/tc39/proposal-async-iteration