RFR: 8245877: assert(_value != __null) failed: resolving NULL _value in JvmtiExport::post_compiled_method_load [v3]

[Leonid Mesnik]

> The crash happens because nmethod might become a zombie before it is enqueued in JvmtiDeferredEventQueue or after it is dequeued from it. The crash is reproduced by serviceability/jvmti/CompiledMethodLoad/Zombie.java. However, it takes ~3K  runs to hit it. I verified the fix by running this test >100K on each platform. Also, I verified that protecting in 'void JvmtiDeferredEventQueue::post(JvmtiEnv* env)' is not enough.

Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:

  post updated.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4602/files
  - new: https://git.openjdk.java.net/jdk/pull/4602/files/9ea2cb9c..2e222f03

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4602&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4602&range=01-02

  Stats: 4 lines in 1 file changed: 1 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4602.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4602/head:pull/4602

PR: https://git.openjdk.java.net/jdk/pull/4602