hi, keeping in mind the concept of env. variable, JAVA_HOME is globaly defined variable, we assigns class path to this variable, on compilation takes place, only one value can be assigned to a variable, it mean only one jvm will be running . so one jvm on one OS.
If more than operating system are installed , you can take have one jvm for each OS.
However question is too much ambigious, if more than one Jdk on one OS, so more than one jvm are there, It is also true , but remember the env.variable, we can assign one value to it,, so at compile time one jvm will be active
How many JVM's can we run in a system?