How To Stop CalendarAgent From Eating CPU

Posted on 8/19/2012 by Robert

Recently ran into an issue with Calendar causing a huge CPU spike. Checking the system.log I noticed the following repeatedly in my log:

CalendarAgent[379] Unexpected EOF, returning last token as fallback

CalendarAgent is essentially Calendar’s backend (that’s how it’s also able to power the notification center). The best resolution I’ve found is to completely clear out the calendar and recreate it. Process I used was as follows:

Remove the Calendar from “Mail, Contacts & Calendars” pref panel (just uncheck from the account). Then go into Calendar and make sure the account is removed. If it’s not, remove it.
Delete ~/Library/Calendars/
Delete ~/Library/Preferences/com.apple.iCal.plist
Go back into the “Mail, Contacts & Calendars” pref panel, put the calendar back. Give it some time to download.

That seems to have worked for me.

8 thoughts on “How To Stop CalendarAgent From Eating CPU”

Daniel on 8/25/2012 at 2:51 pm said:

Thank you so much!! I had been looking all over to find the right thing to do. This worked.

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Andy on 8/31/2012 at 4:14 am said:

Thanks for this, seems to have been the only way I could fix it.

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Lolly on 9/3/2012 at 3:08 pm said:

Robert, you are AWESOME!! I have been troubleshooting for over a week – this issue has been driving me crazy. I tried everything and nothing worked until this fix. Now everything is back working perfectly, fast and smooth with no rainbow balls or s-l-o-w applications. CalendarAgent went from being a big fat slob hogging about 8 GB of virtual memory to a dainty reserved southern bell sipping tea. Thank you so much, Robert!

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lebi on 11/24/2012 at 5:38 am said:

Could you help me with this in Mountain lion ? I have calendars in exchange, icloud and google calendar

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Nick on 1/7/2013 at 2:36 pm said:

This not only worked, but iCal and Reminders now open about 10 times faster than they did previously.

Thank you!

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fetag on 1/30/2013 at 1:26 am said:

Thank you! It’s works for me and tune my Mac faster.

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nicholas on 4/11/2013 at 4:43 am said:

Robert, it sounds like you’ve solved the problem I’m having. Only one issue on my end: neither of those files exist on my computer. Are they hidden by default?

Is there some reason I wouldn’t have those? I’ve got some calendars syncing through iCloud (the problematic ones, I suspect) and others that sync from GMail through Busycal.

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lokioki on 5/1/2013 at 4:04 am said:

i tried this but didn’t work. instead this worked for me:

http://productforums.google.co.....XZkRZzo10I

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