A snippet from https://github.com/victoriadrake/hydra-link-checker

hydra-snippet.py

```python
# Create the Checker class
class Checker:
    # Queue of links to be checked
    TO_PROCESS = Queue()
    # Maximum workers to run
    THREADS = 100
    # Maximum seconds to wait for HTTP response
    TIMEOUT = 60

    def __init__(self, url):
        ...
        # Create the thread pool
        self.pool = futures.ThreadPoolExecutor(max_workers=self.THREADS)


def run(self):
    # Run until the TO_PROCESS queue is empty
    while True:
        try:
            target_url = self.TO_PROCESS.get(block=True, timeout=2)
            # If we haven't already checked this link
            if target_url["url"] not in self.visited:
                # Mark it as visited
                self.visited.add(target_url["url"])
                # Submit the link to the pool
                job = self.pool.submit(self.load_url, target_url, self.TIMEOUT)
                job.add_done_callback(self.handle_future)
        except Empty:
            return
        except Exception as e:
            print(e)
```