sqlx 0.5.2 with a pool size of 1 fails to respond to simultaneous queries

[D1plo1d]

After upgrading to sqlx 0.5.2 whenever I run more then one SQL query in parallel one (or possibly more) of the queries will time out after 30 seconds with:

pool timed out while waiting for an open connection

Downgrading to sqlx 0.5.1 resolves the issue and these same queries complete within an imperceptible amount of time.

I'm using Sqlite with the following configuration:

    // Connect to the database
    let db_options = db_url.parse::<SqliteConnectOptions>()?
        .synchronous(sqlx::sqlite::SqliteSynchronous::Normal);

    let db = SqlitePoolOptions::new()
        .max_connections(1)
        .connect_with(db_options)
        .await?;

Could this be related to the pool changes in #1149 ?

Also downgrading to 0.5.1 was made slightly more difficult because sqlx-core and sqlx-macros were not locked to the same patch release as sqlx. If it would be possible to lock those to the same releass as sqlx, eg. "=0.5.1" that might be handy in debugging future patch release regressions.

[abonander]

Yeah commented on this here: #622 (comment)