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Khan / live-editor

A browser-based live coding environment.
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High CPU/Memory usage in challenges/talk-throughs #332

Open bytorbrynden opened 9 years ago

bytorbrynden commented 9 years ago

(Reported on Zendesk) "I've been programming in Khan Academy recently with my 2013 Macbook Air, and for some reason the website uses over 100% of my cpu and my fans start speeding up to over 6000 RPM.

Does anyone know any solutions to this problem? I noticed that Pamela from the Khan Team uses a Macbook, so there must be some way to avoid this.

Thanks in advanced!" https://khanacademy.zendesk.com/hc/communities/public/questions/202860364-Macbook-air-fans-going-CRAZY-while-coding-JS-in-Khan-Academy

I use Khan Academy on a Mac without any problems at all, and I know a few people who use it on Macbook Airs without any issues like this.

I've asked for more information (such as browser/browser version, and for links to programs where the effect is seen the most).

kevinbarabash commented 9 years ago

It could be Safari 8. I have a MacBook Air. I'm still on Mavericks, but I could try repro-ing this in Safari 7. We could also look at perf differences between Safari and Chrome in general using the browsers' profiling tools. I may also be that there is some background process that's using a good chunk of CPU and then live-editor just pushes it over the top. I wonder what the idle CPU usage is like.

bytorbrynden commented 9 years ago

A bit more information: "Hello Gigabyte Giant, thank you for your response.

As per your request, there is not one specific challenge where it happens. It has been happening ever since I got to the second half of the intro to JS Course and its has happened on every single challenge on the Advanced JS Course. I am using Safari 8."

codeHusky commented 9 years ago

It could have something to do with keeping the live editor in sync with the audio

pamelafox commented 9 years ago

It sounds like it's on both talk-throughs and challenges. We haven't done a performance audit of our code lately, so it could just be happening for people with less RAM/older machines.

I'm going to rename this issue to be about general memory usage and add another report to this thread that is related: I have Norton Security Suite. It has a performance monitoring feature that gives CPU usage percentage per running process. When I was having the problem in the Arrays lesson, I got a message from Norton that IE usage was in the high 90% range. The mouse cursor would not track properly, and Kahn Academy and my PC did not respond to clicks. It happened again today in the Objects section, and specifically in the Modifying Objects and Challenge: Picture Painter lessons. Since the first trouble experience, I have set Norton's performance window open to one side of the screen so I could observe CPU usage. IE CPU usage was very low until part way through Modifying Objects, CPU usage by IE soared to > 90% from the normally < 10% area; mouse performance was fine. Modifying Objects did finish but was not smooth running; i.e., it halted briefly a couple of times. IE CPU usage remand high as I went to Challenge: Picture Painter. It would not load. I saw "Waiting for code to run..." for several minutes before I attempted to shut down. Logging out of Kahn Academy did not respond to mouse clicks, but eventually I logged out. Shutting down IE was similarly balky."