Lessons learned: #612

If you admin a heavily loaded SpamAssassin server...

1. Use SQL for Bayes and AWL data. This allows your spamd processes to store their tokens simultaneously, instead of fighting over the lock for the Berkeley DB files. I use MySQL, postgres works too.
2. If you use network tests, install a local caching nameserver. Even if your nameserver is on the LAN right next to the mail server, it'll be worth it.
3. If you use OCR, make sure that the caching mechanism works. This is especially important in corporate environments where people use images as signatures. For extra points, store the image hashes in SQL too.

Also, the old prefork (--round-robin) algorithm works much better in my case than the new Apache-like scaling algorithm. YMMV.