Why is System.err slower than System.out in Eclipse?

Question

Possible Duplicate:
Java: System.out.println and System.err.println out of order

Why this code

    System.err.println("err");
    System.out.println("out");

prints

out
err

on Eclipse console?

UPDATE

The same code prints in correct order if I run it from command line.

UPDATE

If I fix it as

    System.err.println("err");
    Thread.sleep(5);
    System.out.println("out");

It prints correctly in Eclipse too

Matt Ball · Accepted Answer · 2012-12-01T06:13:51.360

4

It's not slower; they're just not necessarily flushed in order. You can fix that, however:

System.err.println("err");
System.err.flush();
System.out.println("out");

edited Dec 01 '12 at 06:13

answered Dec 01 '12 at 05:28

Matt Ball

But println also calls flush(). See PrintStream.println. – Evgeniy Dorofeev Dec 01 '12 at 05:39
I'm not convinced that your (read: Eclipse's) `println()` implementation does actually call `flush()`. – Matt Ball Dec 01 '12 at 05:53
It does. I debugged it, it comes to java.io.PrintStream.newLine() where it calls flush(). – Evgeniy Dorofeev Dec 01 '12 at 06:02
See my edit. Apparently it's just a long-standing Eclipse bug. – Matt Ball Dec 01 '12 at 06:14

1 Answers1