job.start() and job.run() don't return

[chungwong]

I found job.start().await? and job.run().await? don't return and the program just hangs there.

diff --git a/examples/basic/src/main.rs b/examples/basic/src/main.rs
index d864767..b56c03f 100644
--- a/examples/basic/src/main.rs
+++ b/examples/basic/src/main.rs
@@ -50,7 +50,9 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     .await?;

     // Start the worker to process tasks.
-    job.run().await?;
+    let handle = job.run().await?;
+
+    dbg!(handle);

     Ok(())
 }

❯ cargo run
     Running `target/debug/example-basic`
Sending welcome email to Ferris <ferris@example.com> (user_id: 42)

And it just won't complete and paused there. Is it by design or did I miss something?

[maxcountryman]

Both start and run behave differently: start returns a non-blocking handle which can be awaited, run will block.

Take a look at how the graceful shutdown example handles this.

There's various ways you might design your program, including running jobs in a separate process, so underway lets you decide how you want to do this.

[chungwong]

Could I please have a hint about how to finish a job when there is no more task in the queue.

let job = Job::builder()
    ..
    .build()
    .await?;

job.enqueue(&()).await?;
tokio::spawn(async move { shutdown_signal(&pool).await });

let mut jobs = JoinSet::new();

// BTW, why does it loop twice in the graceful_shutdown example? The JoinSet contains the same job twice?
for _ in 0..2 {
    jobs.spawn({
        let job = job.clone();
        async move { job.run().await }
    });
}

jobs.join_all().await;

Naively the idea will be if there is no task in the queue, then this job has completed and it should return

I tried it with process_next_task but its behaviour is unexpected, sometimes it works, sometimes it will skip steps.

job.worker().process_next_task().await?;

Use case

# not a great use case for using a job queue
# Return when the job is done, but now it hangs unless it is terminated d by ctrl+c
cargo run --bin cli -- run-job-to-completion