arkcompiler_runtime_core/docs/memory-management-SW-requirements.md

1. INTRODUCTION

The main components of Panda memory management:

• Allocators
• GC

Allocators has two purposes:

1. Allocations for the application
2. Allocations for the internal usage by Runtime(Allocations for compiler purposes, for GC internal structures etc)

Garbage Collector: Garbage collector(GC) automatically recycles memory that it can prove will never be used again. GC used to recycle memory allocated as result of application work(objects, compiled code etc).

2. OVERALL DESCRIPTION

Allocator

Alocator Types

• Bump pointer allocator
• Arena Allocator (objects can be deallocated at once(list of arenas, almost at once - O(number of arenas in the list)))
• Freelist allocator
• TLAB
• Run of slots allocator
• Code allocator

Spaces

• Code space (executable)
• Compiler Internal Space(linked list of arenas)
• Internal memory space for non-compiler part of runtime (including GC internals)
• Object space
• Non-moving space(space for non-movable objects)

GC

• Concurrent generational GC (optional - we can disable generational mode)
• GC for classes (optional)
• GC for code cache(optional)

Reference processor.

High level requirements for GC:

• acceptable latency (max pause) for good user experience
• acceptable throughput
• acceptable footprint size

3. KEY FEATURES OF MEMORY MANAGEMENT SYSTEM

Configurable flexible setup "Set of allocators + GC" We can use profile to choose MM configuration for application (for example: we can choose non-compacting GC with freelist allocators for some application if we get acceptable metrics for this)

4. INTERACTION WITH OTHER COMPONENTS

Allocator

• allocator API for runtime
• TLAB API for compiler and interpreter
• interfaces for tools?

GC

• Safepoints
• Reference storage and additional interfaces for MM <-> JNI interaction
• Barriers API for compiler and interpreter
• Possibility to change VRegs for any frame in the stack
• interfaces for tools?

5. ADDITIONAL REQUIREMENTS

• Memory management flexible enough to work with multiple languages.
• provide various statistics data