Memory leak: org.sqlite.JDBC holds classloader of KSP

This happens when running Room:

1. Kotlin compiler daemon loads compiler plugins (KSP) with a new class loader every time it gets a request from Gradle.
2. KSP loads processors(Room) with a child classloader.
3. Room uses org.sqlite.JDBC, which is also loaded with Room’s classloader.
4. org.sqlite.JDBC’s static initializer calls java.sql.DriverManager.registerDriver, which stores the class org.sqlite.JDBC in a static member of java.sql.DriverManager.
5. java.sql.DriverManager is loaded by the root classloader.
6. Therefore all everything loaded with KSP’s classloader can also be reached by the root classloader and never be GC’ed.

Here is a sample project thanks to @BugsBunnyBR.

[BugsBunnyBR]

So, I updated ksp/kotlin/room to the latest version and ran the benchmark again. The behaviour of the memory consumption improved by a lot! Not only that, but the number of live threads stabilised too. Great work folks! 👏 👏 🍰

[BugsBunnyBR]

To the people watching this issue…

I ran the benchmark in a branch with the latest version of room and these are the results.

This is way better than before, even though it seems to use lots of memory I was able to run 50 iterations and didn’t get an out of memory. 👏 👏 I will be waiting a version of ksp to verify the final results.