How to check whether Deno.child is still alive

[rizrmd]

With deno unstable we can spawn a Deno.Child, but how to check whether it is still alive or not ?

[jtoppine]

You can await child.status, or use the promise like so:

child.status.then(() => {
  // process done, do stuff
});

[rizrmd]

I aware of this option, but I need to immediately tell whether child is already killed or not. My current workaround is like this

const isKilled = (child) => {
   return new Promise<boolean>((resolve) => {
       const timeout = setTimeout(() => {
           resolve(false);
       }, 1000);
       child.status.then(() => {
          clearTimeout(timeout)
          resolve(true);
       })
   }
}

This is not perfect, I need to wait at least X timeout (1s in above code) to check whether killed or not...

[rizrmd]

We have child.isKilled in nodejs as boolean, for comparation...

[rizrmd]

I think we can modify child itself to add isKilled property (defaults to false), and attach on "close" event handler to set it to true. Thanks @jtoppine !

[ghost]

Sounds like

const is_child_alive = child =>
 Promise.race(
  child.status.then(_ => false),
  true
 );

Assuming it would be alive until its .status has resolved?

(I can't find the documentation!)

[rizrmd]

Oh wow, TIL... Promise.race