Java garbage Collection algorithm

1. Mark-Clear

Mark objects that need to be recycled

Uniformly reclaim all tagged objects after the tag is complete

Insufficient:

Inefficient, resulting in too much memory fragmentation

2. Copy algorithm

Divide the whole memory into two pieces

When a piece of memory ran out

Copy the surviving object to another piece

Clean up the memory you just used

Advantages: Simple to implement, efficient to run, no debris generation

Insufficient: Space costs are high, reducing memory by half

3. Marking-Sorting algorithm

Let all the surviving objects move toward one end

Clean up memory outside the boundary of the tuning port

4. Collection of Generations

Divide the Java heap into the new generation and the old age

New generation: Every garbage collection has a large number of objects dead, few objects surviving (method 2)

Old age: High object Survival (marker-finishing)

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Java garbage Collection algorithm