Debug Distributed System Codebase | Dataford Interview Questions

Debug a provided distributed-system codebase (concurrency issues such as data races, deadlock, lock contention, rate limiter) in Python.

Asked in the phone screen stage. Implement the corrected rate-limiter core used by the codebase. Requests are processed in arrival order, and each request is [client_id, timestamp]. A request is allowed when that client has made fewer than limit allowed requests in the previous window time units. The implementation must preserve independent state per client and use synchronization correctly when adapted for concurrent callers.

Input and Output

Implement rate_limit(requests, limit, window). Return a Boolean list indicating whether each request is allowed.

Constraints

Requests for each client appear in nondecreasing timestamp order
1 <= limit <= 10^5
1 <= window <= 10^9
0 <= len(requests) <= 10^5
client_id is a hashable identifier

Function Signature

def rate_limit(requests, limit, window):

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