Multiple threads repeatedly provide 'H' and 'O' atoms as callable actions. Design synchronization so that the program outputs a valid sequence representing water molecules, where for every molecule exactly two 'H' actions and one 'O' action are released together. Do not busy-wait; use semaphores/locks/condition variables. Ensure safety (no extra atoms), liveness (no starvation), and scalability under an unbounded stream of atoms. Provide pseudocode and explain correctness.

This question evaluates concurrency and synchronization skills, including thread coordination, use of locks/semaphores/condition variables, and reasoning about safety and liveness properties in concurrent systems.

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Design synchronization for water molecule assembly

Concurrency: Build H2O from concurrent H and O actions

Context

You are given two kinds of threads that repeatedly call the following functions:

hydrogen(releaseHydrogen)
oxygen(releaseOxygen)

Each function receives a callable action:

releaseHydrogen() emits/prints "H"
releaseOxygen() emits/prints "O"

Goal

Design synchronization so that the program outputs a valid sequence of water molecules. For every molecule, exactly two H actions and one O action must be released together (i.e., the three actions for a molecule proceed as a group; groups do not interleave).

Constraints

Do not busy-wait. Use semaphores, locks, and/or condition variables.
Safety: no extra atoms are emitted; every molecule releases exactly two H and one O.
Liveness: no starvation assuming both atom types arrive infinitely often.
Scalability: handle an unbounded stream of atoms without unbounded resource growth.

Deliverables

Pseudocode for hydrogen and oxygen functions and any supporting synchronization primitives.
A brief explanation of correctness (safety, liveness, scalability).

Constraints

Do not busy-wait. Use semaphores, locks, and/or condition variables.

Safety: no extra atoms are emitted; every molecule releases exactly two H and one O.

Liveness: no starvation assuming both atom types arrive infinitely often.

Scalability: handle an unbounded stream of atoms without unbounded resource growth.

Design synchronization for water molecule assembly

Quick Overview

Concurrency: Build H2O from concurrent H and O actions

Context

Goal

Constraints

Deliverables

Solution

Comments (0)

Design synchronization for water molecule assembly

Quick Overview

Concurrency: Build H2O from concurrent H and O actions

Context

Goal

Constraints

Deliverables

Solution

Comments (0)