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COS3721 Exam Questions And Answers
100% Verified And Updated.
1. A deadlocked state occurs whenever ____.
A) a process is waiting for I/O to a device that does not exist
B) the system has no available free resources
C) every process in a set is waiting for an event that can only be caused by another process in the
set D) a process is unable to release its request for a resource after use - Answer✔C
2. One necessary condition for deadlock is ____, which states that at least one resource must be
held in a nonsharable mode. A) hold and wait
B) mutual exclusion
C) circular wait
no preemption - Answer✔B
3. One necessary condition for deadlock is ______, which states that a process must be holding
one resource and waiting to acquire additional resources.
A) hold and wait
B) mutual exclusion
C) circular wait
D) no preemption - Answer✔A
4. One necessary condition for deadlock is ______, which states that a resource can be released
only voluntarily by the process holding the resource. A) hold and wait
B) mutual exclusion
C) circular wait
no preemption - Answer✔D
5. One necessary condition for deadlock is ______, which states that there is a chain of waiting
processes whereby P0 is waiting for a resource held by P1, P1 is waiting for a resource held by
P2, and Pn is waiting for a resource held by P0. A) hold and wait
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B) mutual exclusion
C) circular wait
D) no preemption - Answer✔C
6. The witness software product is a ____.
A) lock-order verifier that uses mutual-exclusion locks to protect critical sections
B) modeler to develop resource allocation graphs
C) driver that can be used to prevent mutual exclusion for nonsharable resources
implementation of the banker's algorithm available for most operating systems - Answer✔A
7. In a system resource-allocation graph, ____.
A) a directed edge from a process to a resource is called an assignment edge
B) a directed edge from a resource to a process is called a request edge
C) a directed edge from a process to a resource is called a request edge
D) None of the above - Answer✔C
8. A cycle in a resource-allocation graph is ____.
A) a necessary and sufficient condition for deadlock in the case that each resource has more than
one instance
B) a necessary and sufficient condition for a deadlock in the case that each resource has exactly
one instance
C) a sufficient condition for a deadlock in the case that each resource has more than once
instance
is neither necessary nor sufficient for indicating deadlock in the case that each resource has
exactly one instance - Answer✔B
To handle deadlocks, operating systems most often _____.
A) pretend that deadlocks never occur
B) use protocols to prevent or avoid deadlocks
C) detect and recover from deadlocks
D) None of the above - Answer✔A
10. Which of the following statements is true?
A) A safe state is a deadlocked state.
B) A safe state may lead to a deadlocked state.
C) An unsafe state is necessarily, and by definition, always a deadlocked state.
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COS3721 Exam Questions And Answers
100% Verified And Updated.
1. A deadlocked state occurs whenever ____.
A) a process is waiting for I/O to a device that does not exist
B) the system has no available free resources
C) every process in a set is waiting for an event that can only be caused by another process in the
set D) a process is unable to release its request for a resource after use - Answer✔C
2. One necessary condition for deadlock is ____, which states that at least one resource must be
held in a nonsharable mode. A) hold and wait
B) mutual exclusion
C) circular wait
no preemption - Answer✔B
3. One necessary condition for deadlock is ______, which states that a process must be holding
one resource and waiting to acquire additional resources.
A) hold and wait
B) mutual exclusion
C) circular wait
D) no preemption - Answer✔A
4. One necessary condition for deadlock is ______, which states that a resource can be released
only voluntarily by the process holding the resource. A) hold and wait
B) mutual exclusion
C) circular wait
no preemption - Answer✔D
5. One necessary condition for deadlock is ______, which states that there is a chain of waiting
processes whereby P0 is waiting for a resource held by P1, P1 is waiting for a resource held by
P2, and Pn is waiting for a resource held by P0. A) hold and wait
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B) mutual exclusion
C) circular wait
D) no preemption - Answer✔C
6. The witness software product is a ____.
A) lock-order verifier that uses mutual-exclusion locks to protect critical sections
B) modeler to develop resource allocation graphs
C) driver that can be used to prevent mutual exclusion for nonsharable resources
implementation of the banker's algorithm available for most operating systems - Answer✔A
7. In a system resource-allocation graph, ____.
A) a directed edge from a process to a resource is called an assignment edge
B) a directed edge from a resource to a process is called a request edge
C) a directed edge from a process to a resource is called a request edge
D) None of the above - Answer✔C
8. A cycle in a resource-allocation graph is ____.
A) a necessary and sufficient condition for deadlock in the case that each resource has more than
one instance
B) a necessary and sufficient condition for a deadlock in the case that each resource has exactly
one instance
C) a sufficient condition for a deadlock in the case that each resource has more than once
instance
is neither necessary nor sufficient for indicating deadlock in the case that each resource has
exactly one instance - Answer✔B
To handle deadlocks, operating systems most often _____.
A) pretend that deadlocks never occur
B) use protocols to prevent or avoid deadlocks
C) detect and recover from deadlocks
D) None of the above - Answer✔A
10. Which of the following statements is true?
A) A safe state is a deadlocked state.
B) A safe state may lead to a deadlocked state.
C) An unsafe state is necessarily, and by definition, always a deadlocked state.
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