Documenting a well known "bug" (design flaw) -- blocking db calls in async io context
WikiPBX uses blocking database calls in a twisted webserver
This is basically a scalability bug that can have a negative impact when the server runs under a heavy load. The bug will be more apparent if there are long running queries or the database is slow for whatever reason.
The problem is that the webserver is running in a non-blocking io environment (eg, twisted web2), but the code makes blocking database calls in many places. So if a database call takes a long time, the whole server will "lock up" for new requests until the long running database call unblocks.
The best solution is to move away from using twisted and non-blocking io and use a more traditional multi-threaded/multi-process webserver, eg, mod_wsgi running under Apache2 or nginx.
