How to turn off auto flush for println?

[peking2]

Hi 

Auto flush is turned off in Java, but turned on in Scala. So Scala is very slow if there are lots of IO. Anyone knows how to turn off it in Scala? and any reason why it's set on by default?

Thanks

Gary

[Simon Schäfer]

How did it come to your mind that println is flushed? When I look to the sources I can't see any difference from println to System.out.println.

A call to println[1] is directly redirected to System.out.println[2].

[1]: https://github.com/scala/scala/blob/v2.10.0/src/library/scala/Console.scala#L234
[2]: https://github.com/scala/scala/blob/v2.10.0/src/library/scala/Console.scala#L75

[Gary Zhao]

I saw this behavior on codeforces.com. Scala was very slow to print out iteratively. Someone told me it's because Scala was configured as "auto flush" and suggested to use mkString before print. I just did some test locally, but didn't see the slowness. Is it because of versioning? They are using 2.9.2 and I'm using 2.10.0? It was fixed somewhere between?

Codeforces: Scala compiler version 2.9.2

Local box: Scala code runner version 2.10.0

Thanks

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[Simon Schäfer]

On 02/12/2013 09:14 PM, Gary Zhao wrote:

I saw this behavior on codeforces.com. Scala was very slow to print out iteratively. Someone told me it's because Scala was configured as "auto flush" and suggested to use mkString before print. I just did some test locally, but didn't see the slowness. Is it because of versioning? They are using 2.9.2 and I'm using 2.10.0? It was fixed somewhere between?

I can't find any changes on this one in the commit history.

[Gary Zhao]

Thanks Simon. Will keep an eye on it to see if I can get some info more.