Bittorrent Bugginess... or how to use up 35% of your CPU doing nothing...

Looks like someone might need to add a little throttling to BitTorrent.

Build 4747 of version 6.0 of the client has a nasty little bug in it - one that should be really easy to fix, but a bug nonetheless.

On my laptop (a single core, old Toshiba Portege M200 Tablet PC), when I'm downloading stuff it will happily sit there, soaking up 35% of my CPU.

What's it doing when it's doing this and how did I figure it out?

Well, I looked at my TaskManager and found that Explorer was taking up 35% of the CPU. I opened up Process Explorer (it's incredibly useful - so download it here; you can find other useful tools at the site) to figure out what was going on in more detail, selected Explorer, and looked in the properties. What I got was this:

Explorer.exe Thread Properties in Process Explorer

The Explorer.exe thread properties in Process Explorer

Hmmm... a single thread is soaking up a lot of CPU. I wonder why that is? Let's pop it open by looking at the Stack for that thread by selecting it and hitting the Stack button.

Explorer.exe Highest CPU usage Thread Stack

The Explorer.exe thread stack in Process Explorer

Hmmm... well, nothing really useful at the top of the stack, and every time I break in, the thread looks the same. Which means it's mostly likely another app rapidly updating the tray icons and spamming it so much that it's just getting hammered and soaking up a lot of CPU.

But how do we find out which app?

I wussed out on this, dear reader. I just started going through the tray and closed apps one by one until I found the one that was doing it. In this case, it looks like it's BitTorrent. I close it down, and the problem goes away. Open it back up, and lo and behold, 35% CPU.

Kinda sucks. Should be an easy fix though - just update the icon on a timer instead of every time something changes in BitTorrent. Hopefully they'll fix it soon.

About the author

Simon Cooke is an occasional video game developer, ex-freelance journalist, screenwriter, film-maker, musician, and software engineer in Seattle, WA.

The views posted on this blog are his and his alone, and have no relation to anything he's working on, his employer, or anything else and are not an official statement of any kind by them (and barely even one by him most of the time).

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