Chore: Attempt to reduce flakiness in integration tests

[macabu]

What is this feature?

1. In integration tests, set sync=OFF if _journal_mode=WAL is set.

Why? From the SQLite docs:

With synchronous OFF (0), SQLite continues without syncing as soon as it has handed data off to the operating system. If the application running SQLite crashes, the data will be safe, but the database might become corrupted if the operating system crashes or the computer loses power before that data has been written to the disk surface. On the other hand, commits can be orders of magnitude faster with synchronous OFF.

Even though it might corrupt the database in case of OS crashes, since these are supposed to be ephemeral databases, these characteristics are not needed. The default is FULL (2).

2. Limit max_open_conn and max_idle_conn to 2. This matches the settings used in E2E tests.

Why?

• Based on previous work from Chore: Reduce flakiness of e2e tests caused by write contention in sqlite #76659
• As well as the following issue database is locked mattn/go-sqlite3#274

It seems that limiting the max connections (especially open) improves the locking errors.

We were previously not setting the max_open_conn at all. This might make some tests slower, but I need to compare them closely.

Why do we need this feature?

This is an attempt to reduce flakiness in integration tests that are failing with database is locked errors.

Who is this feature for?

Contributors.

Which issue(s) does this PR fix?:

N/A

[DanCech]

LGTM

[JohnnyQQQQ]

I agree that we can use it for the tests without running in synchronous mode, but from the change, it would also affect users that currently have wal enabled. We should only disable it with OFF (0) during testing, and continue to have sync on the FULL (2) setting by default, so that a host crash doesn't corrupt their data.

Many of our users rely on stable, non-ephemeral SQLite deployments in their homelabs or any smaller setup, and we should avoid unnecessarily degrading their experience.

[JohnnyQQQQ]

NVM, just saw it's only the testdb, good work 👍