JUICE is a Java ME experimental Java Virtual Machine

Java Virtual Machine

A Java virtual machine is a virtual machine capable of executing Java bytecode. It is the code execution component of the Java software platform. Sun Microsystems stated that there are over 4.5 billion JVM-enabled devices.-Overview:...

 written in C

C (programming language)

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....

 according to the Sun Microsystems

Sun Microsystems

Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...

 specifications. The Juice JVM, designed for real-time Java, was specifically developed to run on the NUXI operating system. The most relevant features of Juice are related to the structure for the heap memory, to the object allocation policy and to the garbage collector

Garbage collector

Garbage collector may refer to:* Waste collector, a person employed to collect waste* A waste collection vehicle* A waste picker, or a dumpster diver* Garbage collection , the detection and pruning of unused or inaccessible data structures...

used.

Heap memory

In Juice, all the available heap memory is shared in "chunks" of pre-fixed size. The memory unit used is the "d-word" (that stands for "double-word"). The actual default size of the chunks is fixed to 64 d-words. The free memory chunks are organized in a linked list, while the chunks occupied by Java objects are connected to each other through a hierarchical structure in a way that resembles the representation of the UNIX file system.

Real-time object allocation policy

The object allocation policy in Juice is strictly connected to the structure used to represent heap memory. Because of this structure, it becomes possible to allocate (and deallocate) Java objects in a time that is dependent only on the size of the object itself (predictability).

The Pay-per-Use garbage collector

The proposed garbage collector is based on a non-copying tracing collector that performs memory reclamation only when a new object has to be allocated. The name of the garbage collector is because the cost paid by the mutator, in terms of wasted time for collector execution, is proportional to the size of the object to allocate.

Authors

Garbage Collector, Heap Memory Management: Corrado Santoro, Roberto Aloi

All the rest: Corrado Santoro