RFR(S): 8210513: Obsolete SyncFlags

[Daniel D. Daugherty]

On 9/7/18 4:48 PM, Mikael Vidstedt wrote:
> Please review this change which obsoletes the SyncFlags flag.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8210513 <https://bugs.openjdk.java.net/browse/JDK-8210513>
> Webrev: http://cr.openjdk.java.net/~mikael/webrevs/8210513/webrev.00/open/webrev/ <http://cr.openjdk.java.net/~mikael/webrevs/8210513/webrev.00/open/webrev/>

src/hotspot/share/runtime/arguments.cpp
     No comments.

src/hotspot/share/runtime/globals.hpp
     No comments.

src/hotspot/share/runtime/objectMonitor.cpp
     No comments.

Thumbs up!

The one use I had for SyncFlags was fixed in this bug:

     8153107 enabling ObjectSynchronizer::quick_enter() on ARM64 causes 
hangs
     https://bugs.openjdk.java.net/browse/JDK-8153107

back in JDK-11-B19... I don't think I have any other uses
for that one...

Dan

>
> * Background (from bug)
>
> The experimental SyncFlags flag can in theory be used to tune how the synchronization primitives behave. The flag was convenient when the various implementations were compared a long time ago.
>
> In practice the only implementation that is used and tested today is the default one. The SyncFlags flag no longer serves the purpose it used to, and is "Unsafe, Unstable" (the documentation of the flag says so explicitly). It should be obsoleted and later removed.
>
>
> Testing: I’m running the normal tier1 testing (still in progress).
>
> Cheers,
> Mikael
>