CODEWITHSUNDEEP
javaintellij-ideaoutput
Turkhan Badalov
Turkhan Badalov

Reputation: 926

IntellijIdea console latency

I have the following code. Main thread starts another thread. After 7 seconds the main thread interrupts another thread.

package com.company;

public class Main {

    public static void main(String[] args) {

        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                for ( int i = 0; i < 10; i++ )
                {
                    System.out.println("Sleeping #" + i);
                    try {
                        Thread.sleep(5000);
                    } catch (InterruptedException e) {
                        System.out.println("Interrupted");
                        e.printStackTrace();
                        continue;
                    }
                }
            }
        });
        t.start();
        try {
            Thread.sleep(7000);
            t.interrupt();
        } catch (InterruptedException e) {}
    }
}

I expected to get such output: 

Sleeping #0
Sleeping #1
Interrupted
java.lang.InterruptedException: sleep interrupted
    at java.lang.Thread.sleep(Native Method)
    at com.company.Main$1.run(Main.java:16)
    at java.lang.Thread.run(Thread.java:748)
Sleeping #2
Sleeping #3
... and so on

But what I get is:

Sleeping #0
Sleeping #1
Interrupted
Sleeping #2
java.lang.InterruptedException: sleep interrupted
    at java.lang.Thread.sleep(Native Method)
    at com.company.Main$1.run(Main.java:16)
    at java.lang.Thread.run(Thread.java:748)
Sleeping #3
... and so on

It first prints "Interrupted". Then the output from the next iteration "Sleeping #2", and then it prints stack trace. Why does it happen? It seems there is latency for printing stack trace. Is it IntelliJ Idea console related problem? Because when I run the program in a native console, it works well.

Upvotes: 0

Views: 48

Answers (1)

pvg
pvg

Reputation: 2729

System.out.println outputs to stdout while Throwable.printStackTrace outputs to stderr. A terminal implementation may buffer each independently and the way the outputs of each stream will be interleaved is not well-defined.

If you want to ensure output from a given thread is displayed strictly sequentially, direct all output to the same stream. In your case, you can either change your printlns to use System.err or use Throwable.printStackTrace(System.out)

Upvotes: 2

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