Can't connect to postgresql database if another mod is using the same driver
daniromome opened this issue ยท 3 comments
Description
I have a proprietary mod that connects to a postgresql database and whenever I try to start the server with both luckperms and my mod luckperms refuses to connect to the database
Reproduction Steps
Have any other mod that uses org.postgresql:postgresql:42.6.0 to connect to a database installed
Config luckperms to use postgresql as a database
Expected Behaviour
Luckperms should be able to connect to the database
Server Details
Fabric 0.14.21 for Minecraft 1.20.1
LuckPerms Version
v5.4.98
Logs and Configs
https://gist.github.com/daniromome/2730a6c0b66209e3e7e1015df22de88f
Extra Details
On my mod the only thing that I do is on initialization sync database tables (create or update with specified schema) and sync the json statistics of each player to those tables every 5 minutes
I have a suspicion that this is due to the postgresql driver using DriverManager.getConnection instead of using its own driver class directly (this is in BaseDataSource.getConnection), and the DriverManager might pick a registered postgresql driver that is different from the one in "this" driver, although the DriverManager does have some classloader safeguards in place but that would only really be useful when each mod/plugin has its own isolated ClassLoader (or when the CL prioritises its own classpath before requesting the parent CL), I don't know how Fabric sets up mod class loading but, for example, this should not happen on Spigot servers.
A solution I can think off the top of my head is to ship a patched version of the driver that does not use the DriverManager to get a connection, but uses the own Driver class directly.
This should probably be reported to pgjdbc/pgjdbc if it hasn't already, but honestly I can't blame them for doing that, as this kind of configuration of "i need to shade/bundle + relocate because someone else might be doing it without relocating but the classloaders are mixed" is far from standard but very brittle.
Please try using v5.4.101 or newer