[RFC]A new journey

[whg517]

fix #226

Hi, scrapy-redis is one of the most commonly used tools for using scrapy, but IT seems to me that this project has not been maintained for a long time. Some of the states on the project are not updated synchronously.

Given the current updates to the Python and Scrapy versions, I wanted to make some feature contributions to the project. If you can accept, I will arrange the follow-up work.

Tasks:

• [x] Added GitHub Action workflow
• [x] Add pep-0517 A build-system independent format for source trees support
• [x] Added adaptation from Python 3.7 to Python 3.10, and removed Python 2 support
• [ ] #283
• [x] Add pytest to test project
• [ ] Use modern sphinx theme -- furo , like pip document

[Sm4o]

It would be super useful to also add the feature of feeding more context to the spiders. Not just a list of start_urls, but a list of json like so:

{
    "start_urls": [
        {
            "start_url": "https://example.com/",
            "sku": 1234
        }
    ]
}

This was already proposed a while back https://github.com/rmax/scrapy-redis/issues/156

[whg517]

Hello @Sm4o , I wrote an example according to your description. Has this achieved your purpose?

import json

from scrapy import Request, Spider
from scrapy.http import Response

from scrapy_redis.spiders import RedisSpider

class SpiderError(Exception):
    """"""

class BaseParser:
    name = None

    def __init__(self, spider: Spider):
        # use log: self.spider.logger
        self.spider = spider

    def parse(
        self,
        *,
        response: Response,
        **kwargs
    ) -> list[str]:
        raise NotImplementedError('`parse()` must be implemented.')

class HtmlParser(BaseParser):
    name = 'html'

    def parse(
        self,
        *,
        response: Response,
        rows_rule: str | None = '//tr',
        row_start: int | None = 0,
        row_end: int | None = -1,
        cells_rule: str | None = 'td',
        field_rule: str | None = 'text()',
    ) -> list[str]:
        """"""
        raise NotImplementedError('`parse()` must be implemented.')

def parser_factory(name: str, spider: Spider) -> BaseParser:
    if name == 'html':
        return HtmlParser(spider)
    else:
        raise SpiderError(f'Can not find parser name of "{name}"')

class MySpider(RedisSpider):
    name = 'my_spider'

    def make_request_from_data(self, data):
        text = data.decode(encoding=self.redis_encoding)
        params = json.loads(text)
        return Request(
            params.get('url'),
            dont_filter=True,
            meta={
                'parser_name': params.get('parser_name'),
                'parser_params': {
                    'rows_rule': params.get('rows_rule'),  # rows_xpath = '//tbody/tr'
                    'row_start': params.get('index'),  # row_start = 1
                    'row_end': params.get('row_end'),  # row_end = -1
                    'cells_rule': params.get('cells_rule'),  # cells_rule = 'td'
                    'field_rule': params.get('text()'),  # field_rule = 'text()'
                }
            }
        )

    def parse(self, response: Response, **kwargs):
        name = response.meta.get('parser_name')
        params = response.meta.get('parser_params')
        parser = parser_factory(name, self)
        items = parser.parse(response=response, **params)
        for item in items:
            yield item

[LuckyPigeon]

@rmax Looks good to me. How do you think? @Sm4o @rmax is a little busy recently, if you don't mind. Feel free to work on it!

[rmax]

Sounds perfect. Please take the lead!

@LuckyPigeon has been given permissions to the repo.

[Sm4o]

That's exactly what I needed. Thanks a lot!

[whg517]

I am working in progress...

[Sm4o]

I'm trying to reach 1500 requests/min but it seems like using a single spider might not be the best. I noticed that scrapy-redis reads urls from redis in batches equal to CONCURRENT_REQUESTS setting. So if I set it to CONCURRENT_REQUESTS=1000 then scrapy-redis waits until all processes are done before requesting another batch of 1000 from redis. I feel like I'm using this tool wrong, so any tips or suggestions would be greatly appreciated

[rmax]

I think this could be improved by having a background thread that keeps a buffer of urls to feed the scrapy scheduler when there is capacity.

The current approach relies on the idle mechanism to being able to tell whether we can fetch another batch.

This is suited for start urls that generate a lot of subsequent requests.

If your start urls generate one or very few additional requests, then you need to use more spider instances with lower batch size.

On Tue, 2 Nov 2021 at 10:46, Samuil Petrov @.***> wrote:

I'm trying to reach 1500 requests/min but it seems like using a single spider might not be the best. I noticed that scrapy-redis reads urls from redis in batches equal to CONCURRENT_REQUESTS setting. So if I set it to CONCURRENT_REQUESTS=1000 then scrapy-redis waits until all processes are done before requesting another batch of 1000 from redis. I feel like I'm using this tool wrong, so any tips or suggestions would be greatly appreciated

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[LuckyPigeon]

@whg517 Please go head! @Sm4o What feature are you working for?

[whg517]

So far, I have done:

• [x] Support python 3.7-3.9，scrapy 2.0-2.5 . And all test is fine.
• [x] Add isort, flake8 to check code
• [x] Add PEP-517 support
• [x] Add gh action

Now I'm having some problems with my documentation. I am Chinese, but my English is not very good, so my English expression ability is not strong. I want someone to take over the documentation.

I think the current document is too simplistic. Perhaps we need to rearrange the structure and content of the document.

[LuckyPigeon]

@whg517 Thanks for your contribution! Please file PR for each feature, then I will review it. Chinese documentations are also welcome, we can rearrange the structure and the content in Chinese version first. And I can do the translation work.

[whg517]

Hello everyone, I will reorganize features later and try to create a new feature PR. As the New Year begins, I still have many plans to do, I will arrange them as soon as possible.

[rmax]

@whg517 thanks for the initiative. Could you also include the pros and cons of moving the project to scrapy-plugins org?

[LuckyPigeon]

@whg517 any progress?