Skip to main content

Computer Science: More Threads = Less Contention?

Have you read The Next Mainstream Programming Language? The original PDF was written by Tim Sweeney, the founder of Epic, the video game company that created Unreal. He really got me thinking about the problems he was facing.

Let's suppose you have 10,000-100,000 objects. Let's suppose that at any moment any one of them might need to "touch" 50 other objects. That's the setup.

Now, let's suppose that you also have a super-lightweight threading system that can handle 100,000 threads. Yeah, sounds far-fetched, but you'd be surprised. Consider allocating a thread for each object. Along with its own thread, each object should have an input queue into which you can post new events. Naturally, this input queue should be protected by a mutex.

The interesting result is that because there are so many threads trying to access so many mutexes, the chances of any two threads trying to access the same mutex to push a new event is relatively small is you assume a random distribution of events. Practically speaking, more fine grained locking can result in reduced thread contention.

Of course, life isn't random, but it's an interesting thought.

Comments

Anonymous said…
I think this is pretty much what ccp games (http://www.ccpgames.com/) is doing. I saw some cool talks about how they are using stackless python to have thousands of threads. Of course they are not exploiting several cores that way, but it shows that the technique can be useful.
Anonymous said…
check out the web server YAWS written in the programming language Erlang.

There are programming models without threads.
jjinux said…
Stackless Python with coroutines is what I was hinting at.
Steve said…
Well, the minute I saw the post I thought "Stackless Python", but I am still trying to understand why you felt it necessary to hint. Why not jusst come out and say what you mean?
jjinux said…
Steve, your question is reasonable. I figured lucky Python people like me weren't the only ones lucky enough to have massively scalable threading systems. I figured the rest of the world would eventually start catching up, so I didn't want to limit the scope of what I was trying to say.
Brandon L. Golm said…
this reminds me of the language I wrote "squirmy" ... it has one thread and one object and can only add two numbers. There's never any contention.
jjinux said…
Squirmy, hmm, I've heard of it. It was interesting in that no one had ever managed to write a buffer overflow or memory leak in that language, right?

I bet if you wrote "Hello World" in Squirmy, it would run *really fast*!

Popular posts from this blog

Ubuntu 20.04 on a 2015 15" MacBook Pro

I decided to give Ubuntu 20.04 a try on my 2015 15" MacBook Pro. I didn't actually install it; I just live booted from a USB thumb drive which was enough to try out everything I wanted. In summary, it's not perfect, and issues with my camera would prevent me from switching, but given the right hardware, I think it's a really viable option. The first thing I wanted to try was what would happen if I plugged in a non-HiDPI screen given that my laptop has a HiDPI screen. Without sub-pixel scaling, whatever scale rate I picked for one screen would apply to the other. However, once I turned on sub-pixel scaling, I was able to pick different scale rates for the internal and external displays. That looked ok. I tried plugging in and unplugging multiple times, and it didn't crash. I doubt it'd work with my Thunderbolt display at work, but it worked fine for my HDMI displays at home. I even plugged it into my TV, and it stuck to the 100% scaling I picked for the othe

Drawing Sierpinski's Triangle in Minecraft Using Python

In his keynote at PyCon, Eben Upton, the Executive Director of the Rasberry Pi Foundation, mentioned that not only has Minecraft been ported to the Rasberry Pi, but you can even control it with Python . Since four of my kids are avid Minecraft fans, I figured this might be a good time to teach them to program using Python. So I started yesterday with the goal of programming something cool for Minecraft and then showing it off at the San Francisco Python Meetup in the evening. The first problem that I faced was that I didn't have a Rasberry Pi. You can't hack Minecraft by just installing the Minecraft client. Speaking of which, I didn't have the Minecraft client installed either ;) My kids always play it on their Nexus 7s. I found an open source Minecraft server called Bukkit that "provides the means to extend the popular Minecraft multiplayer server." Then I found a plugin called RaspberryJuice that implements a subset of the Minecraft Pi modding API for B

Creating Windows 10 Boot Media for a Lenovo Thinkpad T410 Using Only a Mac and a Linux Machine

TL;DR: Giovanni and I struggled trying to get Windows 10 installed on the Lenovo Thinkpad T410. We struggled a lot trying to create the installation media because we only had a Mac and a Linux machine to work with. Everytime we tried to boot the USB thumb drive, it just showed us a blinking cursor. At the end, we finally realized that Windows 10 wasn't supported on this laptop :-/ I've heard that it took Thomas Edison 100 tries to figure out the right material to use as a lightbulb filament. Well, I'm no Thomas Edison, but I thought it might be noteworthy to document our attempts at getting it to boot off a USB thumb drive: Download the ISO. Attempt 1: Use Etcher. Etcher says it doesn't work for Windows. Attempt 2: Use Boot Camp Assistant. It doesn't have that feature anymore. Attempt 3: Use Disk Utility on a Mac. Erase a USB thumb drive: Format: ExFAT Scheme: GUID Partition Map Mount the ISO. Copy everything from