RFR: 8331911: Reconsider locking for recently disarmed nmethods [v5]

[Neethu Prasad]

> **Notes**
> We are spending significant time on acquiring the per-nmethod as all the
> threads are in same nmethod.
> Adding double-check lock by calling is_armed before lock acquisition.
> 
> **Verification**
> 
> Shenendoah
> 
>> % /home/neethp/Development/opensource/jdk/build/linux-x86_64-server-release/images/jdk/bin/java -Xmx1g -Xms1g -XX:+UseShenandoahGC -Xlog:gc ManyThreadsStacks.java 2>&1 | grep "marking roots"
>> [0.706s][info][gc] GC(0) Concurrent marking roots 11.519ms
>> [0.752s][info][gc] GC(1) Concurrent marking roots 9.833ms
>> [0.814s][info][gc] GC(2) Concurrent marking roots 10.000ms
>> [0.855s][info][gc] GC(3) Concurrent marking roots 9.314ms
>> [0.895s][info][gc] GC(4) Concurrent marking roots 8.937ms
>> [1.213s][info][gc] GC(5) Concurrent marking roots 12.582ms
>> [1.340s][info][gc] GC(6) Concurrent marking roots 9.574ms
>> [1.465s][info][gc] GC(7) Concurrent marking roots 12.791ms
> 
> ZGC
> 
>> % /home/neethp/Development/opensource/jdk/build/linux-x86_64-server-release/images/jdk/bin/java -Xmx1g -Xms1g -XX:+UseShenandoahGC -Xlog:gc ManyThreadsStacks.java 2>&1 | grep "marking roots"
>> [0.732s][info][gc] GC(0) Concurrent marking roots 10.694ms
>> [0.782s][info][gc] GC(1) Concurrent marking roots 14.614ms
>> [0.825s][info][gc] GC(2) Concurrent marking roots 12.700ms
>> [0.863s][info][gc] GC(3) Concurrent marking roots 9.622ms
>> [0.904s][info][gc] GC(4) Concurrent marking roots 12.892ms
>> [1.244s][info][gc] GC(5) Concurrent marking roots 12.422ms
>> [1.375s][info][gc] GC(6) Concurrent marking roots 12.756ms
>> [1.503s][info][gc] GC(7) Concurrent marking roots 12.265ms
>> [1.628s][info][gc] GC(8) Concurrent marking roots 12.309ms
>> [1.754s][info][gc] GC(9) Concurrent marking roots 12.996ms
>> [1.879s][info][gc] GC(10) Concurrent marking roots 9.416ms
> 
> **Issue**
> https://bugs.openjdk.org/browse/JDK-8331911

Neethu Prasad has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'openjdk:master' into JDK-8331911
 - 8331911: Remove is_armed check from callers
 - Update full name
 - Address feedback on whitespace and comments
 - 8331911: Fix whitespace
 - 8331911: Reconsider locking for recently disarmed nmethods

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

Changes: https://git.openjdk.org/jdk/pull/19285/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19285&range=04
  Stats: 30 lines in 4 files changed: 22 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/19285.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19285/head:pull/19285

PR: https://git.openjdk.org/jdk/pull/19285