Why does iTunes Match hang on Step 3 on files it has already processed? I recently loaded a few hundred files into iTunes, and it's going through the paces of matching and/or uploading those files. But I've run into a problem, the process becomes stuck on Step 3 and never advances after hours of execution.



After opening Activity Monitor, iTunes is taking anywhere from 300% - 400% CPU time, and an absurd amount of memory / active threads. Note that iTunes functions perfectly fine during this time, except for the iTunes Match process.

When I ran into this problem previously, certain songs were having trouble uploading. I had resolved the problem by creating an AAC version via the right-click options and deleting the original version. In these cases, I think the files were ALWAYS mp3.

However, the problem has resurfaced, but with a much more obnoxious issue. When iTunes Match appears stalled and exhibiting the same high-CPU issue, I open Activity Monitor, select iTunes and click 'Inspect'. Over on the Open Files and Ports tab, I see a number of sockets, network connections, and 3 open files. These files are not only m4a / AAC files, but have already been matched / uploaded.

These files will continue to show up each time I Force Quit and re-open iTunes, restarting the iTunes Match process. It isn't until I use the aforementioned workaround on the affected files that a new batch of files is shown, or I actually make some progress on the iTunes Match view. (At least until it hangs on another song...)

Why is iTunes opening, and more importantly hanging, on files it's already processed?
Have you tried deleting the iTunes preferences files? You can find them on ~/Library/Preferences/com.apple.iTunes.plist and com.apple.iTunes.plist.lockfile
Erasing them will force iTunes to "start fresh" and hopefully fix the problems you have. It won't delete your data (songs, playlists, etc), so it's quite safe to try it.