Mac OS X 10.11.1: cfprefsd thrashing and apparently causing missed keystrokes

Number:rdar://23666465 Date Originated:25-Nov-2015 04:44 PM
Status:Duplicate of 23362398 Resolved:19-Jan-2016 04:55 AM
Product:OS X Product Version:Mac OS X 10.11.1 (15B42)
Classification:Crash/Hang/Data Loss Reproducible:Sometimes
Every day or two, I will find that I can’t type well because the system keeps missing keystrokes. They don’t get queued up and then sent to the screen all at once; they just vanish.

Steps to Reproduce:
1. Try to use my computer for more than two days without rebooting.

Expected Results:
Keyboard input stays fluid.

Actual Results:
Keyboard input gets slow, to the point where I have to reboot. Looking in Activity Monitor, I see cfprefsd (the one owned by root) bouncing between 2-4 and 60-70% CPU every few seconds. When I reboot, cfprefsd is not doing this, and I can type. Thinking they could be related.

In this tweet: David Smith says that it may be related to blued. I’m using Knock to Unlock (, which uses Bluetooth to let you unlock your Mac with your iPhone. I restarted Knock to Unlock on both Mac and iPhone, and cfprefsd is now steady at 0% CPU, so maybe that’s related? Including the results of sudo spindump cfprefsd, which as far as I can tell was captured while the problem was occurring.

Spin dump also posted here:


Comment from Apple Developer Relations:

We need more information to investigate this issue.

Please Enable Bluetooth Logging (to get extra logging) and then create a Diagnostics Report as soon as possible after experiencing the failure, before restarting:

First, enable Bluetooth logging by doing the following: 1. Hold down Shift + Option and click on the Bluetooth menu icon in the upper right. 2. Choose Debug --> Enable Bluetooth Logging

Then generate the Bluetooth Diagnostics report: 1. Hold down Option and click on the Bluetooth menu icon in the upper right. 2. Choose "Create Diagnostics Report on Desktop..." 3. Please attach the BluetoothReporter .zip archive that will be created on the Desktop to this bug report. OR 1. Alternatively, you may execute the following command in sudo /System/Library/Frameworks/IOBluetooth.framework/Resources/BluetoothReporter

AFTER you have captured your logs, feel free to Disable Bluetooth Logging in the same manner. Standard Bluetooth Diagnostic Reports without extra logging are fine for 95% of our bugs; having our Bluetooth Logging enabled causes some log files to grow unbound over time. Disabling our logging will remove those files, even if they have grown large.

Please provide your response or results by updating your bug report.

Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!