UserEventAgent takes up 100% CPU

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UserEventAgent takes up 100% CPU

So all out of a sudden after a restart my Mac goes crazy using 100% CPU for the UserEventAgent. You can't kill the thing, you cant even know what it does! To make a really long story short after quite some searching I found a post suggesting that UserEventAgent may hog your CPU due to some USB Keyboard, and then it hit me, I had bought a new mouse which for indexing reasons I will name as Sharkoon Drakonia (great mouse btw!).

Let me add to the solution below that you can skip the part of adding the -d flag. All it did for me was to bring down UserEvenAgent to 0% and then no proccesses seemed to take up the CPU. Summary showed System 96%, sorting 'All Proccesses' showed top proccess the activity monitor with 3%. How difficult is for a sum to match the parts really? (Did I mention thats a common windows problem? I could buy this problem at half the price, I think they ripped me off!)

Anyhow, let me just say of cource that since 2007 a lot have changed for Macs, now to actually go the Library you have to hit Go->Go to Folder in Finder and then type the path, and of cource we are about 400 builds away of this distant 2007 version of the AppleHIDMouseAgent. Changing the extention from plugin to DISABLED did the trick.

Hey, we may still have problems with mice and keyboards but look, theres a new iTunes, for the new iPhone. Think different.

The answer was found from a post back at 2007, here https://discussions.apple.com/thread/1197549?start=15&tstart=0

Reposting from pinkhandbagOct 29, 2007 6:40 AM (in response to pinkhandbag)

For those of you who are seeing 100% CPU usage and performance issues, here's an update:

In my case (see my previous post for background), I've narrowed it down to a conflict between one of the UserEventAgent plugins (AppleHIDMouseAgent.plugin) and my USB keyboard (Kinesis Freestyle).

I edited /System/Library/LaunchAgents/com.apple.UserEventAgent-Aqua.plist and changed the command-line arguments for UserEventAgent to include -v (verbose logging to stderr) and -d (runs each plugin in a separate thread).

The -v option did not produce anything interesting. The -d option helped though.

Following a fresh reboot with no peripherals plugged in and no applications loaded, the system idles as normal. The moment I plug in my USB keyboard (to either USB port), the UserEventAgent process running AppleHIDMouseAgent.plugin jumps straight to 100% CPU and stays there even after I unplug the keyboard. The only way out that I've found is power-cycling. I also tried booting up with the keyboard plugged in with the same results.

All my other USB devices work fine (Logitech LX7, Hub, HDD, Flash drive), although I do not have another USB keyboard to test with.

While stuck at 100% CPU, watching the inspect pane in Activity Monitor for the AppleHIDMouseAgent.plugin shows the number of faults growing at around 100K+ per second, context switches at 1 per second, while all other fields remain static.

The version of my AppleHIDMouseAgent.plugin (taken from version.plist):

BuildVersion 116
CFBundleShortVersionString 1.2.0
CFBundleVersion 1.2.0b3
ProjectName AppleHIDMouse
SourceVersion 1200303

I no longer use the Apple mouse so I've been able to fix the issue in my case by moving the plugin out of /System/Library/UserEventPlugins. After about an hour of testing, everything seems to be working fine.

Black MacBook 2GHz Intel Core Duo, Mac OS X (10.5)

Posted on Sep 18, 2012 3:39 AM

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