How to send requests to SQLite in Rust in parallel - sql

Question

I want to send some queries to SQL in Rust. To achieve this I'm using the crate sqlx. I send queries to my database file from separate coroutines. And the code works okay if the amount of coroutines is about 1000. If there's more, there's an error
thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: Database(SqliteError { code: 5, message: "database is locked" })', src\main.rs:56:43
I understand that 10 thousand coroutines is too much for one file, but I expect a corouting to wait until the database is unlocked rather than return an error.
Here's my code
use std::error::Error;
use tokio::task::JoinHandle;
use sqlx::sqlite::SqlitePool;
async fn routine(pool: &SqlitePool, age: i32, id: i32) -> Result<String, Box<dyn Error>> {
if age % 2 == 0 {
sqlx::query!("UPDATE users SET salary = salary + 1 WHERE id = ?1", id).execute(pool).await?;
let row = sqlx::query!(r#"SELECT salary FROM users WHERE id = ?1"#, id)
.fetch_one(pool)
.await?;
Ok(format!("{}: {}", id, row.salary))
} else {
let res = sqlx::query!(r#"SELECT salary FROM users WHERE age = ?1 ORDER BY id"#, age)
.fetch_all(pool)
.await?
.iter()
.map(|it| it.salary.to_string())
.collect::<Vec<String>>()
.join(", ");
Ok(res)
}
}
#[tokio::main]
async fn main() {
let n = std::env::args().nth(1).unwrap().parse().unwrap(); // drops if n is 10_000
let pool = SqlitePool::connect("sqlite://database.db").await.unwrap();
let handles: Vec<JoinHandle<_>> = (1..n).map(|_| {
let pool = pool.clone();
tokio::spawn(async move {
routine(&pool, 0, 0).await.unwrap()
})
}).collect();
for handle in handles {
handle.await.unwrap();
}
}
Could you please explain how to wait and not to get errors?