OS X runaway process bug fixed?

Update 2016-04-25: Yes, but not because of what you read below. See this post.

I’ve been experiencing this bug in OS X for so long that I don’t remember if it arrived with El Capitan, or earlier.

Four processes decide periodically to consume a combined 250% CPU: UserEventAgent, launchd, cfprefsd, and mds_stores. The fan starts blowing and the file system is being hammered hundreds or thousands of times a second by cfprefsd.

The Terminal command: sudo fs_usage pid <cfprefsd’s pid> shows lines screaming by on the screen with a .plist file being accessed every few microseconds, a new one created with a temporary suffix, and then renamed back to .plist. I don’t know if that’s happening on the hard drive or the SSD, but if it was on the SSD it’s probably lost a lot of life given how frequently this bug crops up and how long it runs. I often reboot after 12-16 hours and that sometimes fixes the problem—temporarily.

After much searching of the web, several people were reporting the same fix worked. I needed to disable /System/Library/UserEventPlugins/com.apple.cts.plugin by renaming it, and then rebooting.

Sure enough, that works. I’m still trying to find out what purpose that plugin serves and why it decides to go berserk so frequently for so long.

But one thing is for sure. It’s a problem that people have been experiencing for several OS releases, it’s a bitch to diagnose, it slows down the system substantially, and causes needless wear and tear. And it’s an Apple plugin—that they don’t seem too motivated to fix. Given Apple’s track record, this comes as no surprise to me, but it disgusts me just the same.

Update 2016-04-11: Well, it seems the com.apple.cts.plugin is related to Time Machine scheduling. It hasn’t run since I renamed it. Sigh. I guess I have no choice but to reenable it. I just wish Apple would focus on quality instead of expanding their product portfolio with more, buggy crapola.

Author: Tom

Destroyer of software. If I haven't tested it, it hasn't been tested.

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