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8276447: Deprecate finalization-related methods for removal

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Reviewed-by: rriggs, alanb, lancea, darcy, mchung, serb, smarks, prr
This commit is contained in:
Brent Christian 2021-12-08 00:23:15 +00:00
parent 3c2951f738
commit ec7cb6d5d3
62 changed files with 156 additions and 140 deletions
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40
src/java.base/share/classes/java/lang/Object.java
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@ -478,6 +478,12 @@ public class Object {
* A subclass overrides the {@code finalize} method to dispose of
* system resources or to perform other cleanup.
* <p>
* <b>When running in a Java virtual machine in which finalization has been
* disabled or removed, the garbage collector will never call
* {@code finalize()}. In a Java virtual machine in which finalization is
* enabled, the garbage collector might call {@code finalize} only after an
* indefinite delay.</b>
* <p>
* The general contract of {@code finalize} is that it is invoked
* if and when the Java virtual
* machine has determined that there is no longer any
@ -543,27 +549,29 @@ public class Object {
* }
* }</pre>
*
* @deprecated The finalization mechanism is inherently problematic.
* Finalization can lead to performance issues, deadlocks, and hangs.
* Errors in finalizers can lead to resource leaks; there is no way to cancel
* finalization if it is no longer necessary; and no ordering is specified
* among calls to {@code finalize} methods of different objects.
* Furthermore, there are no guarantees regarding the timing of finalization.
* The {@code finalize} method might be called on a finalizable object
* only after an indefinite delay, if at all.
*
* Classes whose instances hold non-heap resources should provide a method
* to enable explicit release of those resources, and they should also
* implement {@link AutoCloseable} if appropriate.
* The {@link java.lang.ref.Cleaner} and {@link java.lang.ref.PhantomReference}
* provide more flexible and efficient ways to release resources when an object
* becomes unreachable.
* @deprecated Finalization is deprecated and subject to removal in a future
* release. The use of finalization can lead to problems with security,
* performance, and reliability.
* See <a href="https://openjdk.java.net/jeps/421">JEP 421</a> for
* discussion and alternatives.
* <p>
* Subclasses that override {@code finalize} to perform cleanup should use
* alternative cleanup mechanisms and remove the {@code finalize} method.
* Use {@link java.lang.ref.Cleaner} and
* {@link java.lang.ref.PhantomReference} as safer ways to release resources
* when an object becomes unreachable. Alternatively, add a {@code close}
* method to explicitly release resources, and implement
* {@code AutoCloseable} to enable use of the {@code try}-with-resources
* statement.
* <p>
* This method will remain in place until finalizers have been removed from
* most existing code.
*
* @throws Throwable the {@code Exception} raised by this method
* @see java.lang.ref.WeakReference
* @see java.lang.ref.PhantomReference
* @jls 12.6 Finalization of Class Instances
*/
@Deprecated(since="9")
@Deprecated(since="9", forRemoval=true)
protected void finalize() throws Throwable { }
}