Is Reqwest thread-safe for concurrent scraping tasks?

reqwest is a popular HTTP client library in Rust, not Python or JavaScript. It is designed to provide a convenient interface for making HTTP requests. When it comes to concurrency in Rust, the language provides strong guarantees through its ownership and borrowing system, which helps prevent data races and other concurrency issues.

The reqwest library is indeed thread-safe for concurrent scraping tasks, provided you use it correctly. This means that you can safely share a reqwest::Client instance across multiple threads and use it to make concurrent HTTP requests. The Client struct is internally reference-counted (Arc in Rust terms) and uses asynchronous I/O for network operations.

Here's a simple example of how you might use reqwest to perform concurrent web scraping tasks in Rust:

use reqwest;
use std::thread;
use std::sync::Arc;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a shared instance of the client
    let client = Arc::new(reqwest::blocking::Client::new());

    // A list of URLs to scrape
    let urls = vec![
        "http://example.com",
        "http://example.org",
        "http://example.net",
    ];

    // Spawn a thread for each URL
    let mut handles = vec![];
    for url in urls {
        let client = Arc::clone(&client);
        let handle = thread::spawn(move || {
            let res = client.get(url).send();
            match res {
                Ok(response) => {
                    println!("Status for {}: {}", url, response.status());
                    // Process response...
                }
                Err(e) => eprintln!("Error requesting {}: {}", url, e),
            }
        });
        handles.push(handle);
    }

    // Wait for all threads to complete
    for handle in handles {
        handle.join().unwrap();
    }

    Ok(())
}

In this example, we create a reqwest::blocking::Client and wrap it in an Arc (atomic reference counter) to enable safe sharing across threads. We then spawn multiple threads, each of which makes a request to a different URL. The Client instance is cloned (which actually just increments the reference count) and moved into the thread closure, where it's used to make the HTTP request.

For asynchronous operations, reqwest also provides an async client, which is similarly thread-safe when used with Rust's async runtime, such as tokio. Here's an example using the async client with tokio:

use reqwest;
use tokio;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create an instance of the async client
    let client = reqwest::Client::new();

    // A list of URLs to scrape
    let urls = vec![
        "http://example.com",
        "http://example.org",
        "http://example.net",
    ];

    // Collect a list of futures
    let mut tasks = vec![];
    for url in urls {
        let client = &client;
        let task = tokio::spawn(async move {
            let res = client.get(url).send().await;
            match res {
                Ok(response) => {
                    println!("Status for {}: {}", url, response.status());
                    // Process response...
                }
                Err(e) => eprintln!("Error requesting {}: {}", url, e),
            }
        });
        tasks.push(task);
    }

    // Await the completion of all the tasks
    for task in tasks {
        task.await?;
    }

    Ok(())
}

In this async example, we create an async reqwest::Client and spawn multiple tasks using tokio::spawn. Each task makes an asynchronous HTTP request to one of the URLs. Since we're using async/await, there's no need for reference counting with Arc because the client is borrowed immutably across the async tasks, and the Rust compiler ensures that the borrow is safe.

Remember that in both examples, proper error handling and response processing should be implemented according to your specific needs. The examples illustrate the basic structure of how to set up concurrent web scraping with reqwest.