What is 'symptomsd" and why is it at times using 60% of my iMac's CPU? There is a system process on my iMac running El Capitan called "symptomsd" that has been consistently bouncing back and forth between about 20% to 60% of the CPU resource on my iMac.

It is running from /usr/libexec/symptomsd. There is a private framework it loads called /System/Library/PrivateFrameworks/Symptoms.framework that itself contains other frameworks called:


ManagedEvent.framework
SymptomAnalytics.framework
SymptomEvaluator.framework
SymptomPresentationFeed.framework
SymptomPresentationLite.framework
SymptomReporter.framework


It doesn't seem to write much to the system log files. In fact the only relevant message in "All Messages" on the iMac is:


  syslogd[46]: Configuration Notice: ASL Module
  "com.apple.networking.symptoms" claims selected messages. Those
  messages may not appear in standard system log files or in the ASL
  database.


There is a preference file at /private/etc/asl/com.apple.networking.symptoms that seems to indicate that logs should be written to /Library/Logs/CrashReporter/com.apple.networking.symptoms.log but that file doesn't even exist on my iMac.

I tried watching what it was doing with tools like fs_usage but I'm not getting much useful information back just lots of "ioctl" requests. I tried manually killing and triggering it to launch again, and it seems to examine all the applications installed on my iMac and then go back to making lots of "ioctl" requests.

Searching on Google all I've been able to determine is that this seems to be one of those things that is shared between OSX and iOS. No information anywhere on what it actually does though.

Anyone have any idea what this process is for or know anywhere it is documented?
I have an iMac and had the same issue. It appears to be a bug in Mac OS X. 

In my case, I had both Ethernet and Wifi turned on for my iMac. Turning Off Ethernet in System Preferences &gt; Network, keeping Wifi as the only connection, prevents the issue completely. Now, the symptomsd consumes about 0.2 ~ 0.3 % CPU load as it's supposed to. 

I started to experience only recently after upgrade to Mac OS X 10.11.1. I guess this is a bug introduced recently.