ISRO2007-42, UGCNET-June2010-II: 37

Question

Semaphores

• A. synchronize critical resources to prevent deadlock
• B. synchronize critical resources to prevent contention
• C. are used to do I/O
• D. are used for memory management

Answer 1

Answer : synchronize critical resources to prevent contention

A semaphore is a way to lock a resource so that it is guaranteed that while a piece of code is executed, only this piece of code has access to that resource. This keeps two threads from concurrently accesing a resource, which can cause problems.

Comments

not getting difference between A) and B) option

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srestha...deadlock...can occur even semaphores are used...

semaphores cannot prevent deadlock...

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Pls help me in understanding --> "As far as I know, only improper usage of semaphore can cause Deadlock , but what I fail to undestand is why we are then implementing it improperly, anything implemented improperly gives bad result or Is it the case that in some code scenario , no matter how much powerful and flawless use of semaphore you try to make --> you cannot avoid dead lock " .