Garbage collection Algorithm (2)-----Tag Removal method

Principle of the Mark clearing method

The Mark clearing algorithm is now the basic idea of garbage collection algorithm. It is roughly divided into two phases: the Mark and purge phases. In the tagging phase, all objects starting from the root node are marked with the root node first. Therefore, an object that is not marked is a garbage object that is not referenced. In the purge phase, all unmarked objects are cleared.

As you can see from the graph, unreachable garbage objects are cleared, and objects that can be reached from the root node survive.

Disadvantages

The biggest problem with the tag cleanup algorithm is that it will cause memory fragmentation, which can be clear on the graph, see, in the living object around, generated a large and small different fragments, discontinuous memory space is less efficient than continuous space, the following algorithm will solve the problem.

Garbage collection Algorithm (2)-----Tag Removal method