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This is a hard difficulty System Design question, commonly asked during HR Screen rounds at Anthropic.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Anthropic during technical interviews.

Implement a thread-safe producer–consumer buffer

Quick Overview

This question evaluates competency in concurrent programming and synchronization primitives, focusing on thread-safe data structure design with FIFO ordering, blocking and timed waits, shutdown semantics, and correctness concerns such as race conditions, deadlocks, and lost wakeups.

Bounded Blocking Buffer with Shutdown and Timeouts

You are asked to design and implement a thread-safe, fixed-capacity producer–consumer buffer that supports multiple producers and consumers.

Functional Requirements

FIFO ordering of items.
Configurable capacity N.
put(item):
- Blocks when the buffer is full.
- A timed put(item, timeout) variant that times out if space does not become available in time.
take():
- Blocks when the buffer is empty.
- A timed take(timeout) variant that times out if no item becomes available in time.
shutdown():
- Unblocks any waiting producers/consumers.
- Rejects new puts after shutdown is invoked.
- After shutdown, consumers may still take remaining items; if the buffer is empty, take should not block.

Non-Functional and Correctness Requirements

Thread-safe for multiple producers and consumers.
Prevent race conditions, deadlocks, and lost wakeups.
Discuss fairness and performance trade-offs.
Analyze time and space complexity.
If time permits: compare a lock-based design (mutex + condition variables) to a lock-free approach.

Assume a Java-like API and execution model (mutex/condition variables, interrupts, and timed waits). You may use a circular array for FIFO ordering.

Quick Overview

Functional Requirements

FIFO ordering of items.

Configurable capacity N.

put(item):

Blocks when the buffer is full.
A timed put(item, timeout) variant that times out if space does not become available in time.

take():

Blocks when the buffer is empty.
A timed take(timeout) variant that times out if no item becomes available in time.

shutdown():

Unblocks any waiting producers/consumers.
Rejects new puts after shutdown is invoked.
After shutdown, consumers may still take remaining items; if the buffer is empty, take should not block.

Non-Functional and Correctness Requirements

Thread-safe for multiple producers and consumers.

Prevent race conditions, deadlocks, and lost wakeups.

Discuss fairness and performance trade-offs.

Analyze time and space complexity.

If time permits: compare a lock-based design (mutex + condition variables) to a lock-free approach.

Assume a Java-like API and execution model (mutex/condition variables, interrupts, and timed waits). You may use a circular array for FIFO ordering.

Implement a thread-safe producer–consumer buffer

Quick Overview

Bounded Blocking Buffer with Shutdown and Timeouts

Functional Requirements

Non-Functional and Correctness Requirements

Solution

Comments (0)

Implement a thread-safe producer–consumer buffer

Quick Overview

Bounded Blocking Buffer with Shutdown and Timeouts

Functional Requirements

Non-Functional and Correctness Requirements

Solution

Comments (0)