RFR(XXS/S): 8230940: Obsolete MonitorBound

[David Holmes]

Hi Dan,

On 2/05/2020 8:57 am, Daniel D. Daugherty wrote:
> Greetings,
> 
> I have a fix for the following bug:
> 
>    JDK-8230940 Obsolete MonitorBound
>    https://bugs.openjdk.java.net/browse/JDK-8230940
> 
> This fix is marked as "XXS" and "S". It is "XXS" because it is primarily
> code deletion and it is "S" because there are 83 changed lines.
> 
> The change in src/hotspot/share/runtime/flags/jvmFlag.cpp is the only
> one that's not obvious. I updated the example with MaxInlineSize to
> replace MonitorBound because both are 'intx' flags with the same range:
> (0, max_jint) so the update was just changing the name.
> 
> Webrev URL: http://cr.openjdk.java.net/~dcubed/8230940-webrev/0-for-jdk15/

Looks good!

One nit in synchronizer.cpp

1172 bool ObjectSynchronizer::is_cleanup_needed() {
1173   if (monitors_used_above_threshold()) {
1174     // Too many monitors in use.
1175     return true;
1176   }
1177   return false;
1178 }

can simply be written as:

bool ObjectSynchronizer::is_cleanup_needed() {
   return monitors_used_above_threshold();
}

Thanks,
David

> This fix has been tested with a Mach5 Tier[1-3] job set on the usual
> Oracle platforms. No regressions.
> 
> The open and closed repos have been searched with the following patterns:
> 
> MonitorBound|check_for_forced_cleanup|is_forced_cleanup_needed|_forceMonitorScavenge|is_MonitorBound_exceeded|needs_monitor_scavenge|InduceScavenge 
> 
> 
> with no unexpected results.
> 
> 
> Here's what we see with the current baseline:
> 
> $ build/macosx-x86_64-normal-server-release/images/jdk/bin/java 
> -XX:MonitorBound=1000 -version
> Java HotSpot(TM) 64-Bit Server VM warning: Temporarily processing option 
> MonitorBound; support is scheduled for removal in 15.0
> Java HotSpot(TM) 64-Bit Server VM warning: Temporarily processing option 
> MonitorBound; support is scheduled for removal in 15.0
> java version "15-internal" 2020-09-15
> Java(TM) SE Runtime Environment (build 
> 15-internal+0-2020-05-01-0300239.dcubed...)
> Java HotSpot(TM) 64-Bit Server VM (build 
> 15-internal+0-2020-05-01-0300239.dcubed..., mixed mode, sharing)
> 
> 
> With the fix in place, here's what we see:
> 
> $ $JAVA_HOME/bin/java -XX:MonitorBound=1000 -version
> Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option MonitorBound; 
> support was removed in 15.0
> java version "15-internal" 2020-09-15
> Java(TM) SE Runtime Environment (build 
> 15-internal+0-2020-05-01-1817475.dcubed...)
> Java HotSpot(TM) 64-Bit Server VM (build 
> 15-internal+0-2020-05-01-1817475.dcubed..., mixed mode, sharing)
> 
> 
> Thanks, in advance, for any comments, questions or suggestions.
> 
> Dan
>