9 months on from my original post, I'm sad to report that this problem still exists (now running the latest version of Yosemite). The longest stretch I've gone with working Spotlight was probably about a month, and lately I've been back to something like a few days. I have re-indexed dozens of times, repaired disk permissions, prayed that software updates would address this, but to no avail. Here are a few specific things I have tried:
1) Removing all non-essential directories from the index (in the privacy section of the spotlight preference pane) and re-indexing.
2) Tracking the console log during each re-index overnight, removing all files that would throw up an error for mds/mdworker such as fonts (which also seems to be a long standing problem: http://www.dextechs.com/osx105spotlight.html), and re-indexing over again.
3) Relaunching spotlight using:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
once it crashed. This works temporarily, but typically not longer than when re-indexing from scratch.
As mentioned before, there are no mds or mdworker processes/messages in the system log that seem to be related to what is causing spotlight to actually crash. For example, here are the mds and mdworker messages from this morning (from the console):
4/24/15 8:00:11.604 AM mdworker[11943]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 8:00:11.604 AM mdworker[11941]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 8:00:11.608 AM mdworker[13403]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 8:00:11.612 AM mdworker[12539]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 8:00:11.618 AM mdworker[13438]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 8:00:11.622 AM mdworker[11940]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.359 AM mdworker[13549]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.363 AM mdworker[13557]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.364 AM mdworker[13570]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.368 AM mdworker[13569]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.372 AM mdworker[13934]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.373 AM mdworker[13840]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.375 AM mdworker32[13998]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 10:14:39.392 AM mdworker[14031]: (ImportBailout.Error:1325) Asked to exit for Diskarb
4/24/15 7:33:50.583 AM SubmitDiagInfo[495]: Removed expired problem report: file:///Library/Logs/DiagnosticReports/mds_2015-03-25-005325_Daniels-MacBook-Pr o-2.crash
4/24/15 7:33:50.587 AM SubmitDiagInfo[495]: Removed expired problem report: file:///Library/Logs/DiagnosticReports/mds_stores_2015-03-25-062325_Daniels-Mac Book-Pro-2.crash
4/24/15 8:00:11.596 AM mds[58]: (Volume.Normal:2464) volume:0x7fd2ab81c000 ********** Bootstrapped Creating a default store:0 SpotLoc:(null) SpotVerLoc:(null) occlude:0 /Volumes/Recovery HD
4/24/15 10:14:39.231 AM mds[58]: (Volume.Normal:2464) volume:0x7fd2ab803000 ********** Bootstrapped Creating a default store:0 SpotLoc:(null) SpotVerLoc:(null) occlude:0 /Volumes/Recovery HD
Spotlight worked fine before 10am and then crashed, but none of the above seems to be related to why this actually happened. There are a few mds_stores crash reports (such as the one mentioned above), but none of them coincide with when Spotlight stops working. Are there other processes except for mds and mdworker that control spotlight?
Any help/advice would be very much appreciated - I am at this point at a complete loss on how to fix this. It's incredibly depressing that something as fundamental as a search tool does not properly work in an operating system.