RFR 8220238 : Enhancing j.l.Runtime/System::gc specification with an explicit 'no guarantee' statement

[Roger Riggs]

Hi,

ok, thanks for the comments.

Any other comments on:
"* Runs the garbage collector in the Java Virtual Machine.
* <p>
* Calling this method suggests that the Java Virtual Machine
* expend effort toward recycling unused objects in order to
* make the memory they currently occupy available for reuse
* by the Java Virtual Machine.
* When control returns from the method call, the Java Virtual Machine
* has made a best effort to reclaim space from all discarded objects.
* There is no guarantee that this effort will recycle any particular
* number of unused objects, reclaim any particular amount of space,
* or complete at any particular time, if at all.
"

Issue:
https://bugs.openjdk.java.net/browse/JDK-8220238

CSR:
https://bugs.openjdk.java.net/browse/JDK-8224760

Webrev:
   http://cr.openjdk.java.net/~rriggs/webrev-gc-8220238-1/

Thanks, Roger

On 05/29/2019 01:38 PM, Aleksey Shipilev wrote:
> On 5/29/19 5:06 PM, Roger Riggs wrote:
>> The language is hard to construct, in part because of the innovations in gc technology that have
>> resulted such a wide range of behaviors and timing.
>>
>> I'll restore the sentence "When control returns"... but I don't think it carries any
>> definite requirement on an implementation. It is benign since 'best effort' is undefined
>> and depends on the unspecified intentions of the implementation(s).
> "When control returns" does mean things for me (GC implementor). We specifically handle blocking
> callers on System.gc() calls in Shenandoah (and partially in Epsilon). I would not be surprised if
> JCK has tests for that as well.
>
> I think "best effort" is orthogonal to blocking behavior.
>
> -Aleksey
>