COMP 3430 Operating systems
Process lifecycle, threads intro
January 31st, 2022
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By the end of today’s lecture, you should be able to:
▶ Describe the lifecycle of a process.
▶ Compare and contrast processes and
The Rocket Book (Public Domain)
Assignment 1
Assignment 1 is now available, let’s check it out.
“States” (Public Domain)
Let’s take a look at states in struct task_struct.
▶ Let’s draw a state transition graph (COMP 2080 & 3030).
▶ The start state is the default state – what’s the default on Linux?
▶ Now identify what the next state is, until we find an end state.
Process states
▶ This is one piece of metadata an OS keeps about a process. ▶ Helps inform:
▶ Scheduling activities.
▶ Maintenance activities.
▶ We can represent these states as a graph 𝐺 = (𝑉 , 𝐸) where:
▶ 𝑉 are the states
▶ 𝐸 are possible transitions between states
Loom (Pixabay License)
▶ Processes → coarse-grained concurrency
▶ Easier to use (fork off and forget)
▶ Everything** is copied (see: man 2
▶ Threads → fine-grained concurrency
▶ Harder to use (we have to manage threads)
▶ Cheaper to use (memory is shared) ( ?)
▶ Process life cycle is modelled by states.
▶ Threads are a more granular form of concurrency.
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