I recently copied over a set of PDF ebooks from an external drive to my “home” folder (usually your login name under Places within Finder) and a few minutes after that my Macbook Pro fan started to go nuts and I noticed my CPU temperature was up near the 70 degree C mark.
Cutting to the chase (fix): Open up System Preferences -> Spotlight Preferences -> Click Privacy button -> Click + button at bottom left and add the directory where you’ve just put your PDF files. In a few minutes, ATSServer will stop going nuts.
I quickly loaded up Activity Monitor (found under Applications -> Utilities in Finder, if nothing shows up after starting Activity Monitor, hit Apple key + 1), sorted processes by CPU descending (by clicking on the CPU column) and noticed that a process called ATSServer was hitting about 60% CPU time with mdworker below it at about 23%.
These two processes were really chewing up processor time and I had no idea what I had done to set this off, having never seen ATSServer before, I googled “What is ATSServer?” and found a forum thread on support.apple.com where people were batting around theories of what was causing ATSServer to go nuts.
For me it turned out to be the PDF books that I had just copied over to my Documents folder. Turns out that Spotlight, Apple’s file and text indexing service, tries to parse text in files, make thumbnails of pdfs (dear god),
and many other things including the kitchen sink.
Here’s an excerpt from Apple on Spotlight (warning PDF file) when they released Spotlight with Tiger (OS X 10.4):
Spotlight is comprehensive. Spotlight searches across your documents, images, movies, music, PDFs, email, calendar events, and system preferences. It can find some- thing by its text content, filename, or information associated with it, known as metadata. This allows you to find a photo by entering the brand of camera that took it, the name of the person who emailed it to you, or the date you last opened it.
I guess Spotlight is a bit too ambitious when it comes to PDF files. Simply copying over 300MB worth of PDF docs shouldn’t cause Spotlight to lose its mind. My guess is that it’s attempting to parse all the text within the PDFs and put those results into Spotlights database. Result: nastiness. PDF’s are exactly “fun” to parse I guess.