RFR: 8267446: Taskqueue code fails with assert(bottom_relaxed() == age_top_relaxed()) failed: not empty [v2]

[Kim Barrett]

> Please review this change to TaskTerminator to no longer verify the queues
> are empty in its destructor. The terminator's destructor may be called after
> the queues have been deleted, as happens in ~ZHeapIterator().
> 
> There is no loss of error checking by this change.  The TaskTerminator
> already verifies the queues are empty on normal termination.
> 
> Testing:
> mach5 tier1, hs-tier6-gc (the latter being where the failure showed up).
> The failure seems to be very intermittent; I've not been able to reproduce it.

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into remove_terminator_assert
 - remove assertion

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4156/files
  - new: https://git.openjdk.java.net/jdk/pull/4156/files/e78caffb..cacf7e97

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4156&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4156&range=00-01

  Stats: 1816 lines in 907 files changed: 862 ins; 49 del; 905 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4156.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4156/head:pull/4156

PR: https://git.openjdk.java.net/jdk/pull/4156