What are the features of the garbage collector in Dart?

The garbage collector in Dart uses the Generational Garbage Collection algorithm.

Key features:

• Generations: Objects are divided into two generations:
  • Young Generation: New objects are created here. Garbage collection in this generation is faster and more frequent because most objects die shortly after creation.
  • Old Generation: Objects that have "survived" several cycles of garbage collection in the young generation are moved here. Garbage collection in the old generation occurs less frequently but takes more time.
• Survivors: Objects in the young generation that are referenced by other objects are considered "survivors" and can be moved to the old generation.
• Collection stages:
  • Minor GC: Fast collection affecting only objects in the young generation.
  • Major GC: Longer collection checking objects in the old generation.
• Advantages of generational collection:
  • Optimization for short-lived objects: Most garbage is quickly removed from the young generation.
  • Reducing pause times: Frequent but short pauses for young generation collection are less noticeable than rare but long pauses for the entire heap.
• Dart VM Garbage Collector:
  • Uses a hybrid approach combining copying (copying collector) for the young generation and mark-and-sweep/compact for the old generation.
  • The copying collector quickly relocates live objects to another memory area, efficiently freeing the current one.
  • Mark-and-sweep in the old generation finds live objects and then relocates them to eliminate memory fragmentation.
  • Works independently of user interface threads, minimizing blocking.

// Example creating objects that will go into the young generation
class MyClass {
  String name;
  MyClass(this.name);
}

void main() {
  var obj1 = MyClass("Object 1"); // Will be created in the young generation
  var obj2 = MyClass("Object 2"); // Will be created in the young generation

  // If objects are not retained by references, they can be collected
  // during the next young generation collection.

  // If these objects live long and are referenced,
  // they can be moved to the old generation.
}