SHARED JAVA JAR FILES

Techniques are disclosed for sharing programmatic modules among isolated virtual machines. A master JVM process loads data from a programmatic module, storing certain elements of that data into its private memory region, and storing other elements of that data into a “read-only” area of a shareable memory region. The master JVM process copies loaded data from its private memory region into a “read/write” area of the shareable memory region. Instead of re-loading the data from the programmatic module, other JVM processes map to the read-only area and also copy the loaded data from the read/write area into their own private memory regions. The private memory areas of all of the JVM processes begin at the same virtual memory address, so references between read-only data and copied data are preserved correctly. As a result, multiple JVM processes start up faster, and memory is conserved by avoiding the redundant storage of shareable data.