In computer science, garbage collection (GC) is a form of automatic memory management. The garbage collector attempts to reclaim memory that was allocated by the program, but is no longer referenced; such memory is called garbage. Garbage collection was invented by American computer scientist John McCarthy around 1959 to simplify manual memory management in Lisp.
Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers write once, run anywhere (WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities that are typically not available in traditional compiled languages.
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.
In computer science, reference counting is a programming technique of storing the number of references, pointers, or handles to a resource, such as an object, a block of memory, disk space, and others.
Java Platform, Standard Edition is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE).
Java and C++ are two prominent object-oriented programming languages. By many language popularity metrics, the two languages have dominated object-oriented and high-performance software development for much of the 21st century, and are often directly compared and contrasted. Java's syntax was based on C/C++.
In software design, the Java Native Interface (JNI) is a foreign function interface programming framework that enables Java code running in a Java virtual machine (JVM) to call and be called by native applications and libraries written in other languages such as C, C++ and assembly.
In computer programming, tracing garbage collection is a form of automatic memory management that consists of determining which objects should be deallocated by tracing which objects are reachable by a chain of references from certain "root" objects, and considering the rest as "garbage" and collecting them. Tracing is the most common type of garbage collection – so much so that "garbage collection" often refers to the tracing method, rather than others such as reference counting – and there are a large number of algorithms used in implementation.
In computer science, asynchronous I/O is a form of input/output processing that permits other processing to continue before the I/O operation has finished. A name used for asynchronous I/O in the Windows API is overlapped I/O.
Jikes Research Virtual Machine is a mature virtual machine that runs programs written for the Java platform. Unlike most other Java virtual machines (JVMs), it is written in the programming language Java, in a style of implementation termed meta-circular. It is free and open source software released under an Eclipse Public License.
In computer science, manual memory management refers to the usage of manual instructions by the programmer to identify and deallocate unused objects, or garbage. Up until the mid-1990s, the majority of programming languages used in industry supported manual memory management, though garbage collection has existed since 1959, when it was introduced with Lisp. Today, however, languages with garbage collection such as Java are increasingly popular and the languages Objective-C and Swift provide similar functionality through Automatic Reference Counting. The main manually managed languages still in widespread use today are C and C++ – see C dynamic memory allocation.
Application virtualization software refers to both application virtual machines and software responsible for implementing them. Application virtual machines are typically used to allow application bytecode to run portably on many different computer architectures and operating systems. The application is usually run on the computer using an interpreter or just-in-time compilation (JIT). There are often several implementations of a given virtual machine, each covering a different set of functions.
Java is a set of computer software and specifications that provides a software platform for developing application software and deploying it in a cross-platform computing environment. Java is used in a wide variety of computing platforms from embedded devices and mobile phones to enterprise servers and supercomputers. Java applets, which are less common than standalone Java applications, were commonly run in secure, sandboxed environments to provide many features of native applications through being embedded in HTML pages.
In computer programming, a green thread is a thread that is scheduled by a runtime library or virtual machine (VM) instead of natively by the underlying operating system (OS). Green threads emulate multithreaded environments without relying on any native OS abilities, and they are managed in user space instead of kernel space, enabling them to work in environments that do not have native thread support.
The Java programming language and the Java virtual machine (JVM) is designed to support concurrent programming. All execution takes place in the context of threads. Objects and resources can be accessed by many separate threads. Each thread has its own path of execution, but can potentially access any object in the program. The programmer must ensure read and write access to objects is properly coordinated between threads. Thread synchronization ensures that objects are modified by only one thread at a time and prevents threads from accessing partially updated objects during modification by another thread. The Java language has built-in constructs to support this coordination.
In software development, the programming language Java was historically considered slower than the fastest third-generation typed languages such as C and C++. In contrast to those languages, Java compiles by default to a Java Virtual Machine (JVM) with operations distinct from those of the actual computer hardware. Early JVM implementations were interpreters; they simulated the virtual operations one-by-one rather than translating them into machine code for direct hardware execution.
Eclipse OpenJ9 is a high performance, scalable, Java virtual machine (JVM) implementation that is fully compliant with the Java Virtual Machine Specification.
Software is said to exhibit scalable parallelism if it can make use of additional processors to solve larger problems, i.e. this term refers to software for which Gustafson's law holds. Consider a program whose execution time is dominated by one or more loops, each of that updates every element of an array --- for example, the following finite difference heat equation stencil calculation:
for t := 0 to T dofor i := 1 to N-1 do new(i) := * .25 // explicit forward-difference with R = 0.25 endfor i := 1 to N-1 do A(i) := new(i) endend
The Java Development Kit (JDK) is a distribution of Java technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java Application Programming Interface (API). It is derivative of the community driven OpenJDK which Oracle stewards. It provides software for working with Java applications. Examples of included software are the Java virtual machine, a compiler, performance monitoring tools, a debugger, and other utilities that Oracle considers useful for Java programmers.
