How to download pictures concurrently with multiple threads in Python

Sometimes it takes hours to download a large number of images - let's fix that

I get it - you're tired of waiting for your program to download image. Sometimes I have to download thousands of images that take hours, and you can't keep waiting for your program to finish downloading these stupid images. You have a lot of important things to do.

Let's build a simple image downloader script that will read a text file and download all the images listed in a folder super fast.

Final effect

This is the final effect we want to build.

Installing dependencies

Let’s install everyone’s favorite requests library.

pip install requests

Now we will see some basic code for downloading a single URL and trying to automatically find the image name and how to use retries.

import requests

res = requests.get(img_url, stream=True)
count = 1
while res.status_code != 200 and count <p>Here we retry downloading the image five times in case it fails. Now, let's try to automatically find the name of the image and save it. </p><pre class="brush:php;toolbar:false">import more required library

import io
from PIL import Image

# lets try to find the image name
image_name = str(img_url[(img_url.rfind('/')) + 1:])
if '?' in image_name:
    image_name = image_name[:image_name.find('?')]

Explanation

Assume that the URL we want to download is:

instagram.fktm7-1.fna.fbcdn.net/vp ...

Okay, this is a mess. Let’s break down what the code does for the URL. We first use rfind to find the last forward slash (/) and then select everything after that. This is the result:

##65872070_1200425330158967_6201268309743367902_n.jpg?_nc_ht=instagram.fktm7–1.fna.fbcdn.net&_nc_cat=111

Now for our second part find a

? and then just take whatever comes before it.

This is our final image name:

65872070_1200425330158967_6201268309743367902_n.jpg

This result is very good and suitable for most use cases.

Now that we have downloaded the image name and image, we will save it.

i = Image.open(io.BytesIO(res.content))
i.save(image_name)

If you’re thinking, “How on earth am I supposed to use the above code?” then you’re right. This is a beautiful function and everything we did above is flattened. Here we also test if the downloaded type is an image, in case the image name is not found.

def image_downloader(img_url: str):
    """
    Input:
    param: img_url  str (Image url)
    Tries to download the image url and use name provided in headers. Else it randomly picks a name
    """
    print(f'Downloading: {img_url}')
    res = requests.get(img_url, stream=True)
    count = 1
    while res.status_code != 200 and count Now, you may ask: "Where is the multiprocessing this person is talking about?". <p></p>this is very simple. We will simply define our pool and pass it our function and image URL. <p></p><pre class="brush:php;toolbar:false">results = ThreadPool(process).imap_unordered(image_downloader, images_url)
for r in results:
    print(r)

Let’s put this in a function:

def run_downloader(process:int, images_url:list):
    """
    Inputs:
        process: (int) number of process to run
        images_url:(list) list of images url
    """
    print(f'MESSAGE: Running {process} process')
    results = ThreadPool(process).imap_unordered(image_downloader, images_url)
    for r in results:
        print(r)

Again, you might be saying, “This is all well and good, but I want to start downloading my 1000 images immediately List. I don't want to copy and paste all this code and try to figure out how to merge everything."

This is a complete script. It does the following:

• Takes as input an image list text file and a process number

• Downloads them at the speed you want

• Print the total time to download the file

• There are also some nice functions that can help us read the file name and handle errors and other stuff

Full script

# -*- coding: utf-8 -*-
import io
import random
import shutil
import sys
from multiprocessing.pool import ThreadPool
import pathlib

import requests
from PIL import Image
import time

start = time.time()

def get_download_location():
    try:
        url_input = sys.argv[1]
    except IndexError:
        print('ERROR: Please provide the txt file\n$python image_downloader.py cats.txt')
    name = url_input.split('.')[0]
    pathlib.Path(name).mkdir(parents=True, exist_ok=True)
    return name

def get_urls():
    """
    通过读取终端中作为参数提供的 txt 文件返回 url 列表
    """
    try:
        url_input = sys.argv[1]
    except IndexError:
        print('ERROR: Please provide the txt file\n Example \n\n$python image_downloader.py dogs.txt \n\n')
        sys.exit()
    with open(url_input, 'r') as f:
        images_url = f.read().splitlines()

    print('{} Images detected'.format(len(images_url)))
    return images_url

def image_downloader(img_url: str):
    """
    输入选项:
    参数: img_url  str (Image url)
    尝试下载图像 url 并使用标题中提供的名称。否则它会随机选择一个名字
    """
    print(f'Downloading: {img_url}')
    res = requests.get(img_url, stream=True)
    count = 1
    while res.status_code != 200 and count 

Save it to a How to download pictures concurrently with multiple threads in How to download pictures concurrently with multiple threads in Python file and run it.

python3 image_downloader.py cats.txt

This is the link to the GitHub repository.

Usage

python3 image_downloader.py <filename_with_urls_seperated_by_newline.txt> <num_of_process></num_of_process></filename_with_urls_seperated_by_newline.txt>

This will read all the URLs in the text file and download them to a folder with the same name as the file name.

num_of_process is optional (by default it uses 10 processes).

Example

python3 image_downloader.py cats.txt

##I would be happy to contribute any advice on how to improve this further respond.

English original address: https://betterprogramming.pub/building-an-imagedownloader-with-multiprocessing-in-python-44aee36e0424

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