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The Java memory model was the first attempt to provide a comprehensive memory model for a popular programming language. [6] It was justified by the increasing prevalence of concurrent and parallel systems, and the need to provide tools and technologies with clear semantics for such systems.
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler.
Executable space protection is an approach to buffer overflow protection that prevents execution of code on the stack or the heap. An attacker may use buffer overflows to insert arbitrary code into the memory of a program, but with executable space protection, any attempt to execute that code will cause an exception.
[1] [2] As in the multi-threaded context where a program executes several threads simultaneously in a shared address space and each of those threads has access to every other thread's memory, thread-safe functions need to ensure that all those threads behave properly and fulfill their design specifications without unintended interaction.
Java memory use is much higher than C++'s memory use because: There is an overhead of 8 bytes for each object and 12 bytes for each array [61] in Java. If the size of an object is not a multiple of 8 bytes, it is rounded up to next multiple of 8. This means an object holding one byte field occupies 16 bytes and needs a 4-byte reference.
The user could also adjust this figure using the Get Info dialog, typically to increase the amount of memory for programs with large needs, like Photoshop. Segmented virtual memory is a further generalization of this mechanism to a large number of segments. Usually the segment table is kept in memory rather than registers.
A polynomial-time algorithm is an Oblivious RAM (ORAM) compiler with computational overhead () and memory overhead (), if given and a deterministic RAM program with memory-size outputs a program with memory-size () such that for any input , the running-time of (,) is bounded by () where is the running-time of (,), and there exists a negligible ...
Modern programming languages like Java therefore implement a memory model. The memory model specifies synchronization barriers that are established via special, well-defined synchronization operations such as acquiring a lock by entering a synchronized block or method. The memory model stipulates that changes to the values of shared variables ...