RFR 9: JDK-8146028 : Common Cleaner for finalization replacements in java.base

[Roger Riggs]

Hi Alan,

On 1/6/2016 10:32 AM, Alan Bateman wrote:
>
>
> On 05/01/2016 18:24, Roger Riggs wrote:
>> The follow on work to adding the Cleaner is to replace uses of 
>> finalization with uses of the Cleaner.
>> For the 'easy' cases in the java.base module, it is useful to 
>> introduce a private Cleaner for the
>> java.base module.  It is proposed to be held weakly, to allow it to 
>> terminate on a lightly loaded
>> system.
>>
>> Webrev for Review:
>> http://cr.openjdk.java.net/~rriggs/webrev-cleaning-factory-8146028/
> This looks okay but can't commonCleaner be final?
yes, fixed.
I prototype a version that kept a WeakReference to the Cleaner so it 
could terminate
if not used.  But it is more complex to make sure the Cleaner would be 
referenced *only* as long
as there were pending Cleanables and depending on its use it might 
thrash starting
a cleaner (thread) and then terminating, necessitating re-creating on 
the next use.
>
>>
>>
>> The 2nd step is using the Cleaner.
>>  - Empty finalize methods should (I think) be removed; but since they 
>> are part of the public spec
>>    the process needs two full releases; so the proposal is to 
>> deprecate them first.
>>    (The JEP 277 necessary changes will be updated when JEP 277 
>> semantics are finalized)
> I assume some of these could just be removed - for example 
> SocketInputStream/SocketOutputStream are package private and aren't 
> part of the API. But maybe you mean that you don't want to touch some 
> java.* classes?
Will remove them; its clearer.

I'll split the finalizers being removed into a separate webrev;
since they don't fit the original description as replacements.

Thanks, Roger

>
> -Alan.