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33 lines
1.3 KiB
Markdown
33 lines
1.3 KiB
Markdown
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---
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title: "Gevent"
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date: 2020-04-09T17:22:52-04:00
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draft: false
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tags: ["python", "concurrency"]
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---
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In my last post I spoke about [concurrency with asyncio](https://brandonrozek.com/blog/pyasyncio/). Now what if you don't want to concern yourself with async/await practices and just want to write synchronous code that executes I/O asynchronously? That's where the library [gevent](http://www.gevent.org/) comes in. It does this by modifying Python's standard library during runtime to call it's own asynchronous versions.
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Last post code's example written in `gevent`.
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```python
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# The first two lines must be called before
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# any other modules are loaded
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import gevent
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from gevent import monkey; monkey.patch_all()
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import time
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def think(duration):
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print("Starting to think for " + str(duration) + " seconds...")
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time.sleep(duration)
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print("Finished thinking for " + str(duration) + " seconds...")
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gevent.wait([
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gevent.spawn(think, 5),
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gevent.spawn(think, 2)
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])
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```
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Notice that the function `think` is written the same as the synchronous version.
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`gevent` is written on top of C libraries `libev` or `libuv` . This combined with the monkey patching can make `gevent` based applications hard to debug if something goes wrong. Otherwise it's a great tool to quickly take advantage of concurrency.
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