Question

Scrapy Concurrent Requests

This is my code snippet

import scrapy
class QuotesSpider(scrapy.Spider):
    name = 'quotes'
    custom_settings = {
        'CONCURRENT_REQUESTS': 25,
        'CONCURRENT_REQUESTS_PER_DOMAIN': 100,
        'DOWNLOAD_DELAY': 0
    }

    f = open("list.txt")
    start_urls = [url.strip() for url in f.readlines()]
    f.close()

    def parse(self, response):
        for quote in response.xpath("//div[@class='border block']"):
            urlgem = quote.xpath(".//div[@class='col-md-4 pull-right']/a/@href").extract()
            if urlgem:
                yield {
                    'text': urlgem,
                }

Using Terminal I execute above code using command

scrapy runspider quotes_spider.py -o quotes.json

list.txt contains 50 URL of same domain separated by lines

As per my understanding the code should put 25 requests to the domain for 25 URL (from a list of 50 URL) and should complete in 2-3 seconds time span and generate file name quotes.json

The output in file quotes.json is coming out as expected but SCRAPY is not performing the task concurrently instead it is fetching URL one by one and takes approximately 55-60 seconds to complete.

Please help!!!

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Hi there @kartikmittal2006,

Scrapy is great as it is built on top of the Twisted library which is an asynchronous networking library that allows you to write non-blocking (asynchronous) code for concurrency, which improves the performance a lot.

However, in order to achieve that, according to the documentation you should run Scrapy as a script as described here:

http://doc.scrapy.org/en/latest/topics/practices.html#run-scrapy-from-a-script

Basically Scrapy is built on top of the Twisted asynchronous networking library, so you need to run it inside the Twisted reactor. I could suggest trying the code example from the documentation link above.

Another thing that you could try doing is using asyncio. The main downside here is that asyncio support in Scrapy is experimental. For more information, you could take a look at the official documentation here:

http://doc.scrapy.org/en/latest/topics/asyncio.html

Hope that this helps! Regards, Bobby