OpenJDK vs Java HotspotVM

Question

Are OpenJDK VM and Oracle Hotspot VM still two different JVMs?

I can\'t seem to find any somewhat official documentation on anything about OpenJDK VM. Even in OpenJD

Answer 1

Oracle HotSpot JVM is based on OpenJDK HotSpot project. So, they are mostly the same VM, except that Oracle JVM has a few additional commercial features, mainly, Java Flight Recorder, Application Class Data Sharing and Cooperative Memory Management.

Runtime flags are almost the same for both VMs; see the complete list using

-XX:+UnlockDiagnosticVMOptions -XX:+UnlockCommercialFeatures -XX:+PrintFlagsFinal

As of JDK 8u131, the only difference is in the following flags (absent in OpenJDK VM):

 bool EnableResourceManagementTLABCache         = true         {product}
 bool EnableSharedLookupCache                   = true         {product}
 bool FlightRecorder                            = false        {commercial}
ccstr FlightRecorderOptions                     =              {product}
 bool LogCommercialFeatures                     = false        {product}
ccstr MemoryRestriction                         = none         {commercial}
 bool ResourceManagement                        = false        {commercial}
 intx ResourceManagementSampleInterval          = -1           {commercial}
ccstr StartFlightRecording                      =              {commercial}
 bool TraceSharedLookupCache                    = false        {product}
 bool UnlockCommercialFeatures                 := true         {commercial}
 bool UseAppCDS                                 = false        {commercial}