RFR 9: 8138696 : java.lang.ref.Cleaner (original) (raw)

RFR 9: 8138696 : java.lang.ref.Cleaner - an easy to use alternative to finalization

Roger Riggs Roger.Riggs at Oracle.com
Wed Oct 14 14:03:36 UTC 2015

Hi Alan,

So any user of the Cleaner can take advantage of the mechanism, for example in a different package or module. For example, Netbeans.

Roger

On 10/14/2015 10:01 AM, Alan Bateman wrote:

On 14/10/2015 14:54, Roger Riggs wrote:

Being able to subclass the XXXCleanable classes allows more efficient implementation of the cleaners in both size and performance. The subclass adds the necessary state for the cleanup and implements the performCleanup method. Only a single object is created (and gc'd), reducing the size of headers and cross references between separate objects. Only the performCleanup method is overridable to maintain the robustness of the Cleaner implementation.

If the XXXCleaner classes are not subclassed, a separate object is needed for the state and behavior. Either that extra object is created by the binding if lambda is used, or by the class needing the cleanup. It is not a big cost but is proposed to optimize the design and implementation. Peter's email [1] provided another description of the use case for subclassing. I'm working on a webrev to show how the Cleaner would be used instead of finalizers and it will show use use of both lambdas and explicit cleanup classes. No issue with sub-classing for the implementation, it's just not clear why they need to be in the public API. -Alan

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