RGL just hit a problem along these lines:
[Tue May 20 12:17:05 2008] [error] [client 213.165.225.132] Plucene::Store::InputStream cannot open /export/home/bob/web/vhosts/london.randomness.org.uk/indexes//_7320.fdx for reading: Too many open files at /opt/csw/share/perl/site_perl/Plucene/Store/InputStream.pm line 35.
A bit of Googling found this: http://web.archive.org/web/20060517002546/http://plucene.minty.org/cgi-bin/w...
which suggested that the problem stems from temp files not being cleaned up. Bob suspects that this might have been caused by reindexing attempts which didn't complete (due to being manually interrupted for some reason). Noting also that File::Temp respects the TMPDIR environment variable, he tried another reindex using a specific tmp directory, and this worked. He's also done something which might make the CGIs use this tmp directory as well but he's not sure it worked.
Bob will follow up to this mail to correct things I got wrong and add stuff I left out. This should probably go in TROUBLESHOOTING.
Kake