GATE CS 2015 Set 1 — Question 30
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.NAT+1 / -0MediumRace Conditions & Critical SectionProcess SynchronizationOperating System
Operating System → Process Synchronization → Race Conditions & Critical Section
Last updated
Question
The following two functions and that share a variable with an initial value of 2 execute concurrently.The number of distinct values that can possibly take after the execution is _________.
P1() {
C = B - 1;
B = 2 * C;
}
P2() {
D = 2 * B;
B = D - 1;
}
Correct answer
3 to 3
Solution
Initial value: . Let be the read and write of in , and be the read and write of in .
- : reads , calculates ; writes .
- : reads , calculates ; writes .
1. then : sets . sets . Final .
2. then : sets . sets . Final .
3.: reads 2 (), reads 2 (). writes , writes . Final .
4.: reads 2 (), reads 2 (). writes , writes . Final .
5.: reads 2 (), reads 2 (). writes , writes . Final .
6.: reads 2 (), reads 2 (). writes , writes . Final .
The distinct possible values for are . The number of distinct values is 3.Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE CS question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Process Synchronization
2026 Set 2 Q23Which one of the following CPU scheduling algorithms cannot be preemptive?2026 Set 1 Q29With respect to deadlocks in an operating system, which of the following statements is/are FALSE?2026 Set 1 Q31In the context of relational database normalization, which of the following statements is/are true?2026 Set 1 Q35Consider a system consisting of instances of a resource , being shared by 5 processes.…2026 Set 2 Q51Consider three processes P1, P2, and P3 running identical code, as shown in the pseudocode below. A…