On 02/07/2016 08:01 PM, Jeremy Manson wrote:
Hadoop seems to use sun.misc.Cleaner:
http://grepcode.com/file/repo1.maven.org/maven2/org.apache.hadoop/hadoop-common/2.7.1/org/apache/hadoop/crypto/CryptoStreamUtils.java
So you may want to keep it around transitionally (a la Unsafe).
JEP 260 [1] was listing sun.misc.Cleaner as a critical API, but
recently, it was decided to "hide" it away into jdk.internal.ref package
which will not be exported [2]. The reasoning was this:
"sun.misc.Cleaner ( was previously listed as a critical internal API,
but on further investigation has been moved to an open issue, for the
following reasons: 1) its primary use in the JDK is within NIO direct
buffers to release native memory. The base module cannot have a
dependency on jdk.unsupported so will need to be updated to use an
alternative cleaner, 2) the usage of Cleaner outside the JDK, as
determined by corpus analysis, has largely been observed to hack into
private fields of the internal NIO direct buffer classes to explicitly
release native memory. As stated in 1), the type of the cleaner used by
NIO direct buffers will have to change. Given this, and the fact that
JDK 9 has a new general purposed cleaner API, java.lang.ref.Cleaner, the
value of keep sun.misc.Cleaner is questionable."
If the decision to remove sun.misc.Cleaner was partly influenced by the
desire to maintain just 2 instead of 3 Cleaner(s), then my proposal to
migrate JDK code to the public API might enable Oracle to reconsider
keeping sun.misc.Cleaner.
[1] https://bugs.openjdk.java.net/browse/JDK-8132928
[2] https://bugs.openjdk.java.net/browse/JDK-8148117
Regards, Peter
Jeremy
On Sun, Feb 7, 2016 at 2:53 AM, Peter Levart <peter.lev...@gmail.com
<mailto:peter.lev...@gmail.com>> wrote:
Hi,
sun.misc.Cleaner has been moved to internal package
jdk.internal.ref recently [1] to clean-up sun.misc namespace. But
now that:
- we have comparable public API (java.lang.ref.Cleaner &
Cleanable) [2]
- we have an internal shared java.lang.ref.Cleaner instance
(jdk.internal.ref.CleanerFactory.cleaner())
- sun.misc.Cleaner is not a special kind of Reference any more in
the JVM [3]
...I think there's no reason to keep this special internal API any
more. It can be replaced with public API.
I propose to remove jdk.internal.ref.Cleaner class and replace its
usages with java.lang.ref.Cleaner and friends [4].
What do you say?
Regards, Peter
[1] https://bugs.openjdk.java.net/browse/JDK-8148117
[2] https://bugs.openjdk.java.net/browse/JDK-8138696
[3] https://bugs.openjdk.java.net/browse/JDK-8143847
[4]
http://cr.openjdk.java.net/~plevart/jdk9-dev/removeInternalCleaner/webrev.01/
<http://cr.openjdk.java.net/%7Eplevart/jdk9-dev/removeInternalCleaner/webrev.01/>
