Same problem here! After some days, it appears from nowhere. Impossible to work with my iMac. Remember me the time with Windows. Also deleting accounts doesn´t solve the problem. "Steve, please come back and show your staff how to create Apple products!" Impossible to believe, that Mountain Lion was tested prior release. Expect to get this fixed - I need to work with my iMac!!!
I was able to get this to stop. Go to:
- System Preferences
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.
I have been fighting the CalendarAgent file ever since upgrading to ML in July. My battery life on a 2011 MacBook Pro 15" is down to 1.5 hours and it gets very hote...!
I have just written to Apple Tech in Peterborough, Canada as follows:
I must record my entire dissatisfaction with this process. I have spent numerous hours with you on the phone and my Mac 15" continues to run hot and battery life down to about 2 hours max.
This has all happened because of the Mountain Lion upgrade as I did not have any of this before.
Now everyone wants to blame other software on my machine. That is completely irrelevant. I have not loaded any add or unusal software, just Office for Mac and Adobe Creative.
Please look at the comments from numerous Apple owners all over the internet and who have a similar problem: Go to http://goo.gl/DFDCd.
I would like to arrange for my machine to go in and be serviced to solve this once and for all.
If I do not get this resolved satisfactorily and soon, I will revert to Windows 7 and tell the world about it.
I may have tracked this down to subcriptions. Verify that all of your subcriptions in Calendar are still valid. I had one that was still trying to find me.com.
Now, before I found this solution I created a CRON job that killed CalendarAgent and iCalExternalSync every minute. This made life so much better; Time Machine actually finish backing up 256MB in just a few minutes not a few hours and my whole system became responsive again.
As always, your milage may vary, but this worked for me. I had to replace my US Holidays subscription and make sure it was pointing to iCloud. Once that was done life was very good again.
More info and this DOES NOT totally fix the problem, but is does help with some things. The problem is fixed until a local icallocaldeamon is spawned and goes away in flash. As soon as that happens Ical External Sync goes hog wild for a bit and then settles down. CalendarAgent peaks but goes back to normal.
The only remaining problems are that iCalExternalSync is using +420MB of memory and growing and CalendarAgent is at +260MB and growing. CPU usage is minimal after spike cause by the local sync kicking in.
I will report with anything additional I can find.
I have now solved my CPU problem. It is a bit brutal but after reading this post:
I have deleted all th plist and preferences as my iCal itself even frooze. Now CPU normal etc and have to reset my calendar settings and that went ok.
I hope this help some of you who were as frustrated as I was!
I found that my .ICS file are bad i.e. too large. Try to export Calendars and then delete your calendars - Import file (s) to a Google Calendar - then Export the file - you will see that the file will be a lot smaller when exported.
This solved my CalendarAgent problem - it is now stable around 70mb.
All my calendars were Google calendars, added originally as delegates, and then apparently duplicated under the accounts system in Mtn. Lions System Prefs.
I removed my entire user/Calendars folder, reconnected my Google account, and let it update all of the calendars. Now everything seems quiet -- no CPU hogging and no disk thrashing (which was even more of a problem than the CPU use)
I had the problem of CalendarAgent using all my CPU power while at the same time getting the following error messages in Calendar :
Access to “Event” in account “iCloud” is not permitted. The server responded "403" to CalDAVWriteEntityQueueableOperation
What helped me was signing out of iCloud (System preferences > iCloud > signout), restart your Mac, and sign back in to iCloud again. I'm not experiencing the error message anymore and CalendarAgent seems to be quite.
Take note that it may take a moment before you have back your calendars, mail, notes, etc. : when you signout all iCloud data gets deleted from you local machine, when you sign back in again all your iCloud mail, notes, calanders get replicated/setup again on your local machine from iCloud.