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Comment by justthistime_ | Hacker News Reader

Java 8 support will run out in a while.

I'm pretty sure it won't "be around for long enough" except if you decide to stay on unmaintained versions full of unfixed security issues.

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It'll run out by September 2017, if not later:

http://www.oracle.com/technetwork/java/eol-135779.html

Do we believe that the affected software will not be able to move to the replacement APIs in the next two years? Honestly I'd expect that by fall 2017, the only versions of Cassandra, Spark, etc. that need sun.misc.Unsafe will themselves be unmaintained and full of unfixed security issues.

Herein lies the problem. As other commenters have pointed out there is no alternative way to do thing performantly without Unsafe. These "core" (as in used everywhere not core to java) libraries don't use Unsafe for fun but often because there is no other way to do something without compromising way too much on speed or other things. If Java 9 had replacements for Unsafe things it would be one things but it doesn't.

JNI

JNI has a very high per-call overhead. It is not an effective alternative to many things in Unsafe. For example, in Hadoop when using short-circuit local reads, the client determines if the file descriptor it has cached is still valid by doing a read from a memory-mapped file. The only way to do this with decent performance is with Unsafe#getLongVolatile. In contrast, JNI methods can't be inlined, often require copying memory back and forth, and don't work well with the just-in-time compiler.

In many cases, the overhead of JNI is too large to even use it, unless you move a large portion of the program out of Java. If Oracle goes through with this removal it will be a huge problem for Java and the JVM ecosystem.

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