46 lines
1.2 KiB
Markdown
46 lines
1.2 KiB
Markdown
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Lecture Topic: Producer Consumer & Reader Writer Problem
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[Lecture 20](https://lms.unb.ca/d2l/le/content/231539/viewContent/2623161/View)
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If you were to use two semaphores and a mutex you can have multiple producers and multiple consumers.
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Producer
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```c
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while(true) {
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// produce am item
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wait(empty)
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wait(mutex)
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buffer[index] = item
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index++
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signal(mutex)
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signal(full)
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}
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```
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Consumer
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```c
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while(true) {
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// consume an item
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wait(empty)
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wait(mutex)
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item = buffer[index]
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index--
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signal(mutex)
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signal(full)
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}
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```
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[Slides Chapter 7](https://lms.unb.ca/d2l/le/content/231539/viewContent/2622059/View)
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In the reader writer problem, you can encounter the "First reader-writer problem", in which the writer process never writes. A "second reader-writer problem" in which when a writer is ready to write, no reader is available. These problems can sometimes be solved by kernel reader writer locks.
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[Dining Philosopher problem](https://en.wikipedia.org/wiki/Dining_philosophers_problem)
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[Slides Chapter 8](https://lms.unb.ca/d2l/le/content/231539/viewContent/2623159/View)
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Deadlock Characterization:
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Deadlocks can occur if four conditions are true simultaneously
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- Mutual exclusion: only one process can use a resource
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