Stale Data Occurs in Multi-CPU Machines When One Thread Modifies

question 34

Multiple Choice

Stale data occurs in multi-CPU machines when one thread modifies shared data and a second thread accesses that data later, but sees the data value before the change took place. What is required to guarantee that the second thread sees the updated data, not stale data when access to the shared data occurs in two different methods?

• A) One method needs to acquire then release the lock after modifying the data.
• B) Both methods need to acquire then release the lock after modifying or reading the data.
• C) Never change any shared object data in multi-CPU machines.
• D) Never use locks for any shared data in multi-CPU machines.

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Definitions:

Least-squares Regression

A statistical method used to determine the line of best fit by minimizing the squared differences between observed values and those predicted by a linear function.

Mixed Cost

Expenses that have both fixed and variable components, varying with the level of activity but not in direct proportion.

High-low Method

A technique used in cost accounting to estimate variable and fixed costs based on the highest and lowest levels of activity.

Fixed Manufacturing Cost

Costs that do not change with the level of production, such as rent, salaries, and insurance.