I still remember when Firefox switched to using SQLite for most of its internal data. It felt like it took 3 or 4 releases to work out the concurrency and block

I still remember when Firefox switched to using SQLite for most of its internal data. It felt like it took 3 or 4 releases to work out the concurrency and blocking issues. I remember back in the day it had lots to do with fsync. Has most of that been worked out between SQLite and newer Linux kernels, or is that a pit waiting for other applications that go the same route?