{
  "cells": [
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "%matplotlib inline"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Thread pool executor\n\n``Asyncio``/``concurrent`` heavily changed from python ``3.4`` to ``3.7``, better read the docs\nand do some tutorials. Asyncio is preferred over plain concurrent module. \n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import concurrent.futures\nimport urllib.request\n\nURLS = [\n    \"http://www.foxnews.com/\",\n    \"http://www.cnn.com/\",\n    \"http://europe.wsj.com/\",\n    \"http://www.bbc.co.uk/\",\n    \"http://some-made-up-domain.com/\",\n]"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Retrieve a single page and report the url and contents\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "def load_url(url, timeout):\n    with urllib.request.urlopen(url, timeout=timeout) as conn:\n        return conn.read()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "We can use a with statement to ensure threads are cleaned up promptly\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:\n    # Start the load operations and mark each future with its URL\n    future_to_url = {executor.submit(load_url, url, 60): url for url in URLS}\n    for future in concurrent.futures.as_completed(future_to_url):\n        url = future_to_url[future]\n        try:\n            data = future.result()\n        except Exception as exc:\n            print(\"%r generated an exception: %s\" % (url, exc))\n        else:\n            print(\"%r page is %d bytes\" % (url, len(data)))"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
      "language": "python",
      "name": "python3"
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    "language_info": {
      "codemirror_mode": {
        "name": "ipython",
        "version": 3
      },
      "file_extension": ".py",
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      "name": "python",
      "nbconvert_exporter": "python",
      "pygments_lexer": "ipython3",
      "version": "3.8.10"
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