Crawler configuration

Colly’s default configuration is optimized for scraping smaller number of sites in one job. This setup isn’t the best if you’d like to crawl millions of sites. Here are some tweaks:

Use persistent storage backend

By default Colly stores cookies and visited URLs in memory. You can replace the built-in in-memory storage backend with any custom backend. See more details here.

Use async for long running jobs with recursive calls

By default Colly blocks while the request isn’t finished, so recursively calling Collector.Visit from callbacks produces constantly growing stack. With Collector.Async = true this can be avoided. (Don’t forget to use c.Wait() with async.)

Disable or limit connection keep-alive

Colly uses HTTP keep-alive to enhance scraping speed. It requires open file descriptors, so max-fd limit can be easily reached with long running jobs.

HTTP Keep-alive can be disabled with the following code:

c := colly.NewCollector()
    DisableKeepAlives: true,