RFR: 8348960: [leyden] compiler/c1/TestConcurrentPatching.java is stuck

[Aleksey Shipilev]

This is seen in GHA, and reproduces well on my machine as well:


$ CONF=linux-x86_64-server-fastdebug make images test TEST=compiler/c1/TestConcurrentPatching.java
<stuck, timeout>


Test runs with `-Xcomp`. gdb "thread apply all bt" shows the compilers are idle. Supplying `-XX:-UseLockFreeCompileQueues` makes the test pass. I believe there is a bug in `UseLockFreeCompileQueues` in leyden repo. 

The comment hopefully explains what happens here. This is a corner case that seems to reproduce on the test that runs `-Xcomp` with a very few compilations.

Additional testing:
 - [ ] GHA
 - [ ] Linux x86_64 server fastdebug, `compiler/c1/TestConcurrentPatching.java`, 100x

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

Commit messages:
 - No iffs, no butts
 - Fix

Changes: https://git.openjdk.org/leyden/pull/30/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=30&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348960
  Stats: 20 lines in 1 file changed: 18 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/leyden/pull/30.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/30/head:pull/30

PR: https://git.openjdk.org/leyden/pull/30