What we removed in 4.0:
SQLite support (I like it but this database got locked
when several users use gitlab at once)
This is a pitty! I am sure there are many small teams where sqlite is totally sufficient.
Have you been able to measure and determine the problems with sqlite more precisely? It would be interesting to see at which point (number of concurrent users) the problems occur. Also it just reads like some data accessing backend is not properly closing connection / file access, so blocking might be just a bug, not a sqlite limitation.
I personally do like having such important infrastructure like bugtrackers as simple as possible, beeing able to setup anytime anywhere with sqlite backend is really a plus in changing environments.
One important solution is to switch from journal mode to WAL mode. Journal mode (the default) makes readers block writers and vice versa. WAL mode makes it so only writers block writers.
Have you been able to measure and determine the problems with sqlite more precisely? It would be interesting to see at which point (number of concurrent users) the problems occur. Also it just reads like some data accessing backend is not properly closing connection / file access, so blocking might be just a bug, not a sqlite limitation.
Did you read http://www.sqlite.org/lockingv3.html ?
I personally do like having such important infrastructure like bugtrackers as simple as possible, beeing able to setup anytime anywhere with sqlite backend is really a plus in changing environments.