Previous 1 2 3 Next 82 Replies Latest reply: Mar 11, 2015 8:29 AM by Amanda Marks1
msl422004 Level 1 Level 1

I use GMail/GCal for email and calendar. I had my GCal synced to iCal in Snow Leopard, but stopped using it in Lion. After upgrading to Mountain Lion I decided to give it a shot again, mostly to get my appointments in the notification center. However, I noticed that a process called "CalendarAgent" was using tons of CPU and memory: over 100% and 400 mb, respectively. It was slowing my computer down and killing my battery life.


After some investigation, it seems like Delegation (calendars that are shared to me by other GCal users) may be part of the problem. If I remove all of the calendars from the "Delegation" tab in the Preferences for Calendar, then CalendarAgent goes down to 0-1 % CPU and 156mb memory. It still seems a little high on the memory front, but at least the CPU isn't out of control now.


This is obviously not an optimal solution. I need to access the shared calendars to schedule meetings with my coworkers. Has anybody run into this issue? Any ideas for fixing this? Is it a Mountain Lion bug?

MacBook Pro (15-inch Mid 2010), OS X Mountain Lion
Reply by shornby on Aug 11, 2012 10:57 AM Helpful

I was able to get this to stop.  Go to:


  • System Preferences
  • Notifications


Click the "Calendar" entry on the left.  Un-Check everything on the right.  The entry moves to the bottom (or below the line).  After that, my CPU went straight down to a normal percentage, system temp dropped, etc.


This is a *bug*.  Let's hope a fix comes out so we can enable notifications again!


Hope this helps.



All replies

  • Ron Kiley Level 1 Level 1

    I went in and disabled all accounts on Mac. I rarely use iCal on Mac, just iPad and iPhone.

    They seem to be still working and have bee monitoring Activity Monitor for a few minutes and Calendaragent hasn't reared its ugly head again.


    My late 2011 iMac crashes if it goes to sleep. I changed preferences to never sleep but darken screen. An ok workaround for a desktop but it would be unacceptable it I had a MBP.


    Both solutions are crappy workarounds. Very unhappy with ML upgrade.

  • Ron Kiley Level 1 Level 1

    I lied it came back with a vengeance, not too much CPU but 2.0 gb real mem and 3.32 gb virtual mem. **** what a dog!

  • AndyOrmsby Level 1 Level 1

    Similar experience here, but not as severe. Google Mail/Calendar accessed using Apple Mail and Calendar on OSX 10.8.  Multiple accounts and delegations.


    Occasionally, Calendaragent gets busy and consumes 90-100% of CPU (according to ActivityMonitor).  I thought about killing it but didn't. In the end, I just quit Calendar, noted that Calendaregent continued to run but eventually spun down from 90% to ~0% CPU, then restarted Calendar. 


    I've not seen it grow beyond 130MB of real memory (140MB virtual).

  • msl422004 Level 1 Level 1

    Update: I've been monitoring this for the last few days. I've kept my iCal data pared down - no shared calendars or delegates, just my own GCal. Memory usage has been growing slowly from about 140 MB up to 240 MB (real). Every once in a while CPU spikes up to 100% or so, but I can't tie those spikes to anything in particular.


    Also, it looks like others are complaining about this on Twitter and othe threads in these forums, so we are not alone.

  • bchemel Level 1 Level 1

    Same problem here. Have two linked google accounts in Mail, Contacts & Calendars. CalendarAgent has been spiking to ~100% of new MBPr and eating ~400MB when doing so.


    When CPU is spiked, lots of entries in system.log that look like:

    Jul 31 11:53:20 xxxxxxxxx.local CalendarAgent[28267]: Unexpected EOF, returning last token as fallback

  • AndyOrmsby Level 1 Level 1

    Update at the end of the day: No more spikes of activity that I've noticed. Memory use has actually shrunk - to around 120MB. I've made no attempt to prune my calendar.

  • Ron Kiley Level 1 Level 1

    I continually have to force quit it thru activity monitor or it just takes all memory. Just started it today and it started at 21 mb real and in 3 minutes it is up to 468 mb and rising.

  • dloomer Level 1 Level 1

    Same here. Battery life has severly taken a hit since upgrading to ML the day it was released -- new MB Air (13") that used to get 7-8 hours battery life is down to 2-3.  Like the above poster, I am able to alleviate the issue by killing the process, but I don't know of a way to permanently keep it off.


    As soon as the laptop starts getting hot, I notice a sudden decrease in battery % and see the estimated time remaining at something crazy (like 1:20 when I have 63% battery left). Reliably, CalendarAgent is always eating most of my CPU in Activity Monitor. Once I kill the process, the estimated time remaining rebounds to about 3x what it was estimating previously.

  • dloomer Level 1 Level 1

    Good call bchemel - I'm noticing the same console log entries when the CPU spikes.


    The big mystery is: Why is this thread the only recent hit (and one of just three total) on a Google search for that error message? You'd think we were the only 6 people in the world with this problem

  • Ron Kiley Level 1 Level 1

    I can't believe it either that there only six people in Appleland that have this problem. It reached an all time onhigh of using 7.39 gb of virtual memory. I am not sure what delegations are but it happens no matter what I have running. I have to keep Activity Monitor running and visible at all times and have to force quit CalendarAgent whenever it gets over 100 Mb of real memory. What a pain.

    I was wondering if I should just redownload and reinstall Mountain Lion. Not sure if I can even do that nor what the ramifications would be.

    This is so frustrating.

  • dloomer Level 1 Level 1

    I should point out I haven't seen memory spikes, only CPU spikes, and in my case I don't have delegations set. I even tried setting my non-iCloud accounts to check manually rather than every 15-60 minutes and that didn't help. Should probably try the same for iCould as well though ...

  • pulkitsinghal Level 1 Level 1

    In addition to all the memory and CPU hogging, my screen keeps flickering until I forcefully kill the calendar agent

  • pascal k Level 1 Level 1

    Same pronblem here. After installing Mountain Lion on my MacBookAir the CalenderAgent Process grow up to 98% and the fan is working on very High Rotation. :-(

    No solution yet...

  • dht101 Level 1 Level 1

    Been waiting for "the answer" too.  Here is what worked for my.  I had three subscriptions that were located on my mac (not on icloud).  I deleted those three calendars and calendar agent is behaving again. I kind of wonder if the calendar agent EOF error was waiting for a response from a calendar server that just wasn't giving responses . . . but calendar agent kept pinging it for a response.  Hope this helps some.

Previous 1 2 3 Next