RFR: 8344332: (bf) Migrate DirectByteBuffer to use java.lang.ref.Cleaner [v4]

[Aleksey Shipilev]

> DirectByteBuffers are still using old `jdk.internal.ref.Cleaner` implementation. That implementation carries a doubly-linked list, and so makes DBB suffer from the same issue fixed for generic `java.lang.ref.Cleaner` users with [JDK-8343704](https://bugs.openjdk.org/browse/JDK-8343704). See the bug for the reproducer.
> 
> We can migrate DBBs to use `java.lang.ref.Cleaner`.
> 
> There are two pecularities during this rewrite.
> 
> First, the old ad-hoc `Cleaner` implementation used to exit the VM when cleaning action failed. I presume it was to avoid memory leak / accidental reuse of the buffer. I moved the relevant block to `Deallocator` directly. Unfortunately, I cannot easily test it.
> 
> Second is quite a bit hairy. Old DBB cleaning code was hooked straight into `Reference` processing loop. This was possible because we could infer that the weak references we are processing were DBB cleaning actions, since old `Cleaner` was the only use of this code. With standard `Cleaner`, we have lost this association, and so we cannot really do this from the reference processing loop. With the patched version, we now rely on normal `Cleaner` thread to do cleanups for us. Because of this, there is a new outpacing opportunity window where reference processing might have been over, but cleaner thread has not reacted yet.
> 
> Tests show that DirectBufferAlloc tests are still surviving this, possibly due to exponential sleep-backoff already built in. See the reclamation path in `Bits.unreserveMemory`: https://github.com/openjdk/jdk/blob/c207cc7e705d3f449f2387324d86cfb31ce40c44/src/java.base/share/classes/java/nio/Bits.java#L106-L186
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `java/nio java/io`
>  - [x] Linux AArch64 server fastdebug, `java/nio java/io`
>  - [ ] Linux x86_64 server fastdebug, `all`
>  - [ ] Linux AArch64 server fastdebug, `all`

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Review feedback and benchmarks

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22165/files
  - new: https://git.openjdk.org/jdk/pull/22165/files/b115ec46..f8ecbd60

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22165&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22165&range=02-03

  Stats: 116 lines in 7 files changed: 108 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/22165.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22165/head:pull/22165

PR: https://git.openjdk.org/jdk/pull/22165