Reduced performance in Java 9.0.1 (vs 8u152)

Martin Traverso mtraverso at
Thu Jan 4 23:04:55 UTC 2018

> One thing I noticed that seems to affect performance is a change in the
> implementation of Unsafe.copyMemory(). JDK-8149159 added some
> verification code.

The decompressor uses Unsafe.copyMemory() for the tail of the data block,
so it shouldn't be called so frequently that it would affect performance
that much. Do you think the mere presence of those checks (and, thus, extra
code in the optimization window) may have some effect on the JIT's ability
to optimize the rest of the code?

- Martin
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