> SonarCloud reports multiple incorrect double-checked locking cases in 
> `sun.java2d.CRenderer`. For example:
> 
>   Arc2D arcToShape;
> 
>   ...
>             if (arcToShape == null) {
>                 synchronized (this) {
>                     if (arcToShape == null) {
>                         arcToShape = new Arc2D.Float();
>                     }
>                 }
>             }
> 
> `Arc2D` contains fields that are not `final`. `arcToShape` is not `volatile`. 
> This makes it an incorrect DCL.
> This code is used by Mac OS, do it would probably blow up some time later on 
> M1.
> 
> This is the candidate fix that preserves the semantics. I am doing this fix 
> blindly so far, without testing on real Mac OS. But maybe there is no need to 
> do any of this, because the setter methods overwrite the contents of all 
> these objects under their own sync. So, maybe we can just allocate those 
> objects without DCL-backed caching and pass them in?

Aleksey Shipilev has updated the pull request incrementally with one additional 
commit since the last revision:

  Drop DCL and useless synchronization completely

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2948/files
  - new: https://git.openjdk.java.net/jdk/pull/2948/files/c81b9ea2..d912f559

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2948&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2948&range=00-01

  Stats: 80 lines in 1 file changed: 0 ins; 70 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2948.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2948/head:pull/2948

PR: https://git.openjdk.java.net/jdk/pull/2948

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