Is it possible to stream large files with urllib3?

Yes, it is possible to stream large files with urllib3. Streaming is a useful technique when working with large files, as it allows you to process the file in chunks without loading the entire file into memory. This can be especially important in environments with limited memory or when dealing with very large files.

Here is how you can use urllib3 to stream a large file in Python:

import urllib3

# Create a PoolManager instance for making requests
http = urllib3.PoolManager()

# The URL of the large file you want to stream
url = "http://example.com/largefile.zip"

# Open a connection to the URL and request to stream the response
response = http.request('GET', url, preload_content=False)

# Choose a chunk size (number of bytes). This is the size of each part of the file you'll handle at a time.
chunk_size = 1024

# Stream the content, chunk by chunk
with open('largefile.zip', 'wb') as out:
    while True:
        data = response.read(chunk_size)
        if not data:
            break
        out.write(data)

# Release the connection
response.release_conn()

In the code example above, preload_content=False is passed to the request method to ensure that urllib3 does not automatically load the entire response content into memory. Instead, you read the content in chunks by repeatedly calling response.read(chunk_size).

Remember to handle the cleanup properly by calling response.release_conn() to release the connection back to the connection pool for reuse. This is important to prevent resource leaks.

If you're using urllib3 within a context that requires handling network errors or retries, you might want to use urllib3's Retry and error handling features to make your streaming process more robust.