How do I handle persistent connections with the Requests library?

In Python, the requests library doesn't provide a built-in method to establish a persistent connection with a server as it's designed for sending individual HTTP requests. Each time you make a request using requests.get() or requests.post(), a new connection is made to the server, and after the response is fetched, the connection is closed.

However, the requests library does support a feature called "Session" objects which allows you to persist certain parameters across requests. When you use a Session, it uses urllib3's connection pooling. So if you make multiple requests to the same host, the underlying TCP connection will be reused, which can result in a significant performance improvement.

Here's an example of how you can use a Session to make multiple requests:

import requests

# Create a session object
with requests.Session() as session:
    # Modify session headers if needed
    session.headers.update({'User-Agent': 'my-app/0.0.1'})

    # First request
    response_one = session.get('https://httpbin.org/cookies/set/sessioncookie/123456789')
    print(response_one.text)

    # Second request (reuses the same TCP connection)
    response_two = session.get('https://httpbin.org/cookies')
    print(response_two.text)

In the above example, the Session object is used to make two GET requests. The second request will reuse the TCP connection established by the first request if the server supports it (keep-alive).

When you're done with a session, it's good practice to release the connection back to the pool so that it can be reused. When you use the Session in a with statement as shown above, it is automatically closed when the block is exited.

If you don't use the with statement, you should close the session manually by calling session.close() to ensure that the connections are released:

# Without the with statement
session = requests.Session()
# Make requests using session...
session.close()

Keep in mind that a persistent connection doesn't mean the server will maintain the state of your session (like being logged in) unless you manage the cookies or tokens needed for authentication between requests.

If you need to establish a persistent connection for a use case that requests can't handle, you would have to use a different library such as http.client in the Python standard library, or third-party libraries like aiohttp for asynchronous operations, or websockets for WebSocket connections.