RFR: 8290344: Start/stop displaysync affects performance in metal rendering pipeline [v2]

[Alexey Ushakov]

> Reuse displaysync thread for subsequent updates

Alexey Ushakov 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 one additional commit since the last revision:

  8290344: Start/stop displaysync affects performance in metal rendering pipeline
  
  Reuse displaysync thread for subsequent updates

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9512/files
  - new: https://git.openjdk.org/jdk/pull/9512/files/b0036fb9..1f17b0be

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9512&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9512&range=00-01

  Stats: 73947 lines in 1600 files changed: 37572 ins; 29641 del; 6734 mod
  Patch: https://git.openjdk.org/jdk/pull/9512.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9512/head:pull/9512

PR: https://git.openjdk.org/jdk/pull/9512