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Parallelism Revisions #43

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d188f8e
redefine parallelism/concurrency, define workers
jespiron Jan 10, 2025
6ea3a8a
shorten pre-existing example
jespiron Jan 10, 2025
ddfdba5
reorg outline
jespiron Jan 10, 2025
9ea5041
update multithreading
jespiron Jan 10, 2025
f61838b
update
jespiron Jan 10, 2025
c035a4b
motivate interthread communication
jespiron Jan 10, 2025
486498b
reduce pacing for data races
jespiron Jan 10, 2025
d46926f
fix formatting
jespiron Jan 10, 2025
c211e3b
migrate Atomics slide
jespiron Jan 10, 2025
0f06b4c
migrate Message Passing slides
jespiron Jan 10, 2025
5c88ca9
motivate message passing
jespiron Jan 10, 2025
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update
jespiron Jan 10, 2025
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shorten pre-existing example
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@jespiron
jespiron committed Jan 10, 2025
commit 6ea3a8a851c83b7a027f32b417bf90c0dc0e65e6
58 changes: 33 additions & 25 deletions week10/slides.md
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Expand Up @@ -41,23 +41,25 @@ paginate: true

We divide tasks among workers.

* In hardwareland, we call these workers **processors** or **cores**.
* In hardwareland, we call these workers **processors** and **cores**.

* In softwareland, <!-- "we give these workers a different name" -->
* "Processors/CPUs" => Processes
* "Processors" => Processes
* "Cores" => Threads

* **Key difference:** Parallelism utilizes **multiple** processors/cores
* Some concurrency models don't!


<!-- Note:

Students coming from 122 may be unfamiliar with hardware terminology,
so I added this to clarification.

Alternate suggestion is to replace all instances of "cores / processors"
with "threads / processes"
Students coming from 122 may be unfamiliar with processors/cores,
so I added this for clarification.

Alternate suggestion is to remove mention of hardware,
so that this slide is shortened to
"Examples of workers:
* Processes
* Threads"
-->


Expand All @@ -73,47 +75,53 @@ with "threads / processes"
---


# Parallelism vs. Concurrency (Examples)
# Parallelism vs. Concurrency: Examples
<div class="columns">
<div>

## Parallelism

* Have one processor work on loading the webpage, while another updates the progress bar
* Processing 100x100px regions of an image on each core
* 8 cores, 8 threads
* 4 threads load the webpage, 4 threads update the progress bar

</div>
<div>

## Concurrency
## Alternate Concurrency Model

* 1 core, 1 thread
* When blocked on loading the webpage, update the progress bar
Comment on lines +92 to +93
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A lot of our students will not really understand what "blocked on loading the webpage" means. Do you think you could come up with another example?

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This was @jurplel’s example, reworded
His slide originally had two examples (loading webpage, image processing)

How about the second example?

One thread switches between each image region

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  • As we load a webpage, take a break sometimes to update the loading progress bar

I think it is important to spell out what exactly "blocked" means here, at least the first time we bring it up


* One core
* As we load a webpage, take a break sometimes to update the loading progress bar
* Often used to do other things while we wait for blocking I/O operations
* e.g. Running garbage collection while we wait for a response over the network

</div>
</div>


---


# Today: Parallelism
- Threads
- Synchronization
- Message Passing
- `Send` and `Sync`
- More Synchronization
- Multithreading
- Interprocess Communication
- Shared Memory
- Synchronization
- Message Passing
- `Send` and `Sync`


---


# Terminology: Threads

* Dangerously overloaded term—can mean one of many things
* For this lecture, we define it as a "stream of instructions"
* In Rust, language threads are 1:1 with OS threads
* **Key point:** Threads share the same resources
For this lecture, we define it as a "stream of instructions"

<!--Speaker note:

Emphasize that "thread" is overloaded term
In Rust, language threads are 1:1 with OS threads

-->

---

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