RFR 9: 8064932: test java/lang/ProcessBuilder/Basic.java: waitFor didn't take long enough

[David Holmes]

Hi Martin,

On 18/11/2014 2:49 PM, Martin Buchholz wrote:
> Hi David,
>
> I'm still hoping to persuade you (and others) to fix the long-standing
> return-early bug in Object.wait.

Are you referring to the low level mechanics or specifically to the 
nanosecond version below?

> As new support for my position I offer the "at least" in  JLS
> https://docs.oracle.com/javase/specs/jls/se8/html/jls-17.html#jls-17.2.1
>
> """
>
> If this is a timed wait, an internal action removing t from m's wait
> set that occurs after at least millisecs milliseconds plusnanosecs
> nanoseconds elapse since the beginning of this wait action.
>
> """
>
> --- a/src/java.base/share/classes/java/lang/Object.java
> +++ b/src/java.base/share/classes/java/lang/Object.java
> @@ -444,16 +444,17 @@
>        *             this exception is thrown.
>        */
>       public final void wait(long timeout, int nanos) throws
> InterruptedException {
> -        if (timeout < 0) {
> -            throw new IllegalArgumentException("timeout value is negative");
> -        }
> +        if (nanos != 0) {
> +            if (timeout < 0) {
> +                throw new IllegalArgumentException
> +                    ("timeout value is negative");
> +            }
>
> -        if (nanos < 0 || nanos > 999999) {
> -            throw new IllegalArgumentException(
> -                                "nanosecond timeout value out of range");
> -        }
> +            if (nanos < 0 || nanos > 999999) {
> +                throw new IllegalArgumentException
> +                    ("nanosecond timeout value out of range");
> +            }
>
> -        if (nanos >= 500000 || (nanos != 0 && timeout == 0)) {
>               timeout++;
>           }

That seems overly complex - after checking for valid values of timeout 
and nanos you simply need:

if (nanos > 0) timeout++;

to ensure the >= requirement.

But seriously we should just deprecate this version as we're not likely 
to get any underlying OS mechanisms for doing nanosecond resolution 
timed blocking actions.

David
-----

>
>
> On Mon, Nov 17, 2014 at 6:11 PM, David Holmes <david.holmes at oracle.com> wrote:
>
>>> On 11/17/2014 2:54 PM, Martin Buchholz wrote:
>>>>
>>>> Returning early is EVIL.
>>
>>
>> Yet every OS seems to allow it <sigh>