Implement a multithreaded web crawler with a thread pool, then survive the GIL and asyncio follow-ups
The reported Anthropic concurrency round: the crawler is twenty minutes, the follow-ups are the interview. Why threads work despite the GIL, what asyncio buys you, and where the semaphore goes. The answers, with the race condition graders plant.
Updated Aug 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.
The reported Anthropic concurrency round: the crawler is twenty minutes, the follow-ups are the interview. Why threads work despite the GIL, what asyncio buys you, and where the semaphore goes. The answers, with the race condition graders plant.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
