JDK 10 RFR of 8185092: Data race in FilterOutputStream.close

[Alan Bateman]

On 26/07/2017 18:52, Brian Burkhalter wrote:
> :
>
> --- a/src/java.base/share/classes/java/io/FilterOutputStream.java
> +++ b/src/java.base/share/classes/java/io/FilterOutputStream.java
> @@ -25,6 +25,8 @@
>   
>   package java.io;
>   
> +import java.util.concurrent.atomic.AtomicBoolean;
> +
>   /**
>    * This class is the superclass of all classes that filter output
>    * streams. These streams sit on top of an already existing output
> @@ -50,7 +52,7 @@
>       /**
>        * Whether the stream is closed; implicitly initialized to false.
>        */
> -    private boolean closed;
> +    private AtomicBoolean closed = new AtomicBoolean();
>   
>       /**
>        * Creates an output stream filter built on top of the specified
> @@ -162,10 +164,9 @@
>        */
>       @Override
>       public void close() throws IOException {
> -        if (closed) {
> +        if (closed.getAndSet(true)) {
>               return;
>           }
> -        closed = true;
>   
>           Throwable flushException = null;
>           try {
This is probably okay but would be good to check the impact on startup 
(as FileOutputStream is loaded early as part of initializing System.out 
and err).

-Alan