Recall & Review
beginner
What is a deadlock in an operating system?
A deadlock is a situation where two or more processes are stuck waiting for each other to release resources, so none can proceed.
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beginner
Why does a deadlock cause the system to freeze?
Because processes wait forever for resources held by each other, no process can continue, causing the system to stop making progress.
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intermediate
Name the four conditions necessary for a deadlock to occur.
1. Mutual exclusion: resources cannot be shared simultaneously.<br>2. Hold and wait: processes hold resources while waiting for others.<br>3. No preemption: resources cannot be forcibly taken away.<br>4. Circular wait: a cycle of processes each waiting for a resource held by the next.
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intermediate
How does circular wait contribute to deadlocks?
Circular wait means each process waits for a resource held by another process in a cycle, so none can proceed or release resources.
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intermediate
What is one common method to prevent deadlocks?
One method is to prevent one of the four necessary conditions, such as disallowing hold and wait by requiring processes to request all resources at once.
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Which of the following is NOT a condition for deadlock?
✗ Incorrect
Preemption allowed means resources can be taken away, which prevents deadlocks. Deadlocks require no preemption.
What happens to processes involved in a deadlock?
✗ Incorrect
Processes in deadlock wait forever for resources held by others, causing a standstill.
Why does deadlock freeze system progress?
✗ Incorrect
Deadlock causes processes to wait endlessly for resources, so no progress is made.
Which condition involves a cycle of processes each waiting for a resource held by another?
✗ Incorrect
Circular wait is the condition where processes form a cycle waiting for each other's resources.
How can deadlocks be prevented?
✗ Incorrect
Allowing preemption means resources can be taken from processes, preventing deadlocks.
Explain in your own words why deadlocks cause a system to freeze.
Think about what happens when everyone waits for something no one releases.
You got /3 concepts.
List and briefly describe the four conditions that must exist for a deadlock to happen.
Remember the four rules that create a deadlock cycle.
You got /4 concepts.