Corrupt data is committed in WAL when DB is near kernel mmap limit

To reproduce

When DB experiences errno=12 because it's near mmap kernel limit it can start writing corrupt data in WAL. That then crash the database and suspends the tables.

The database should instead fail to commit the data.

2025-02-25T11:11:42.427397Z C server-main unhandled error [job=io.questdb.network.IODispatcherLinux@793138bd, ex=
io.questdb.cairo.CairoException: [12] could not mmap column [fd=472922493926, size=1048576]
]

can result in _event.i files being 0 sizes on the disk. This then can either crash the DB or suspend WAL table.

QuestDB version:

8.1.2

OS, in case of Docker specify Docker and the Host OS:

Docker, Linux

File System, in case of Docker specify Host File System:

ext4

Full Name:

Alex Pelagenko

Affiliation:

QuestDB

Have you followed Linux, MacOs kernel configuration steps to increase Maximum open files and Maximum virtual memory areas limit?

• Yes, I have

Additional context

No response

Start by reproducing the errno=12 condition on Linux near the kernel mmap limit with a WAL table, then trace the commit path that produces zero-size _event.i files. Done means the commit fails without corrupting WAL data, and the database or table does not crash or become suspended.