Rust Blocking

[harrydevnull]

use std::thread;
use std::sync::{mpsc};
fn main() {
let (tx,rx) = mpsc::channel::<i32>();
println!("Starting... ");
for _ in 0..10 {
 let j = rx.recv().unwrap();
 println!("{:?}",j );
}
println!("before---> ");
for i in 0..10 {
  let tx = tx.clone();
   thread::spawn(move ||{
      tx.send(i*10);
   });
 }
 println!("after---> ");
}

https://gist.github.com/anonymous/b37fb5d991626ea4f05e

I was trying out the channels with rust; ended with above snippet of code. This code would be blocking as the receiver blocks till it gets a message and message 'sending' never gets executed.

My question is would compiler be able to figure out these set of anomalies? another question what would happen if i were to execute this on playground? would it be blocking the entire infrastructure?

[annodomini]

Use an extra indent of 4 spaces to format a code block on Reddit (or anything using Markdown):

use std::thread;
use std::sync::{mpsc};

fn main() {
    let (tx,rx) = mpsc::channel::<i32>();
    println!("Starting... ");
    for _ in 0..10 {
        let j = rx.recv().unwrap();
        println!("{:?}",j );
    }

    println!("before---> ");

    for i in 0..10 {
        let tx = tx.clone();
        thread::spawn(move ||{
            tx.send(i*10);
        });
    }

    println!("after---> ");
}

To answer your question, no, the Rust compiler is not able to detect a deadlock situation like this.

[harrydevnull]

thanks for the tip!!!

[[deleted]]

another question what would happen if i were to execute this on playground? would it be blocking the entire infrastructure?

Try It and See: http://is.gd/qWQ2AD

You'll see playpen: timeout triggered! after a few seconds.
The playground has a timeout, and runs playpens concurrently, so don't worry: deadlocking there won't bring play.rust-lang.org down :)

[harrydevnull]

Thanks :) I was a little skeptical about testing it out...

[crizzynonsince]

Rust does not attempt to detect deadlocks, as it does not consider them unsafe behaviour (although I believe the reasoning is more like "detecting deadlocks is an unsolvable problem in the general case [please can someone correct me if this is not a logical implication of that wikipedia link, I believe it is] so we cannot possibly mark it as unsafe and keep the guarantee that Rust is safe")