[jdk17] RFR: 8271251: JavaThread::java_suspend() fails with "fatal error: Illegal threadstate encountered: 6" [v3]

[Patricio Chilano Mateo]

> Hi,
> 
> Please review this small patch. When self-suspending, a JavaThread might reach SafepointSynchronize::block() with a state of _thread_in_vm which is not listed as a valid state for safepoint polling. There are a couple of simple ways to fix this. As suggested by @dholmes-ora  we can avoid the handshake machinery altogether and directly self-suspend. Since this issue is intermittent and in tier7 which I didn't run as many times as other lower tiers it escaped my testing of 8270085.
> 
> Testing in mach5 tiers1-7. I also reproduced the test failures locally and verified that now both hs202t002.java and ThreadSuspendSelf.java are passing. 
> 
> Thanks,
> Patricio

Patricio Chilano Mateo has updated the pull request incrementally with one additional commit since the last revision:

  move log statement back inside loop

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/283/files
  - new: https://git.openjdk.java.net/jdk17/pull/283/files/4ecb736e..a73c0094

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=283&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=283&range=01-02

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/283.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/283/head:pull/283

PR: https://git.openjdk.java.net/jdk17/pull/283