Today I was getting this warning in my server event log:
event id 4164 and 4103
Catalog: AnchorProject. A master merge was started due to an external request.
Since it was flodding my event viewer I didnt even see the other issues there... but one of the servers CPU was in max usage all the time (100%, but since we had 2 CPU task manager shows 50% total usage)...
Well, as I was digging up more info here is what I came up with and how I solved this issue:
1: I was getting an error on a certain page from within a site ( a custom list view ) that referenced the wrong master page - /_layouts/application.master. Since the celler page was in the list and not in the /_layouts/ folder this was blocked by ASP.NET
2: The caller user was my search user, lucky it is a unique user so I could be sure it was invoked by the indexer
So, after I fixed / deleted these 2 pages - the indexer stopped trying to index them, and 30 seconds after that the errors were gone and CPU back to normal...
Hope this helps you guys too, I will update if I get more info on this.