Hey,what is size 0 means?? ,can't open connection??

[yuyang-ok]

I am new to sqlx , When I using sqlx in my project.

let mut conn = pool.try_acquire();
                let get_conn_time = std::time::Instant::now();
                while conn.is_none() {
                    tokio::time::sleep(Duration::from_millis(100)).await;
                    // don't even try.
                    if sender.is_closed() {
                        return;
                    }
                    conn = pool.try_acquire();
                    if conn.is_none() && get_conn_time.elapsed() > Duration::from_secs(10) {
                        tracing::warn!(
                            "after {:?} still can't get conn: sql:{} connection size:{} idle:{}",
                            get_conn_time.elapsed(),
                            load_data_sql.as_str(),
                            pool.size(),
                            pool.num_idle()
                        );
                    }
                    if conn.is_none() && get_conn_time.elapsed() > Duration::from_secs(60) {
                        let _ = sender.send(Err(datafusion::error::DataFusionError::Internal(
                            "can't get pgsql conn".to_string(),
                        )));
                        return;
                    }
                }

I can't acquire new connection.

2024-01-16T05:45:49.796829Z WARN ThreadId(16) runtime.spawn{kind=task task.name= task.id=67784 loc.file="src/core/query/src/datasource/table_provider/external_view/mysql_table.rs" loc.line=188 loc.col=13}: src/core/query/src/datasource/table_provider/external_view/mysql_table.rs:199: after 40.746810864s still can't get conn: sql:select `CTLG_ID` as `CTLG_ID`,`NAME` as `NAME`,`DESC` as `DESC`,`LOCATION_URI` as `LOCATION_URI`,`CREATE_TIME` as `CREATE_TIME` from `CTLGS` connection size:0 idle:0

you see the size is 0 ,is this mean sqlx can't establish new connection??