java basics garbage collection

Question

is garbage collection algorithm in java "vendor implemented?"

Answer 1

Definitely vendor dependent. GCJ and the Sun VM use totally different garbage collectors, for example.

Answer 2

Yes, and not only that, each JVM can contain more than one garbage collection strategy:

• Sun
• JRockit
• IBM

Answer 3

From the introduction paragraph to Chapter 3 of the Java Virtual Machine Specification:

For example, the memory layout of run-time data areas, the garbage-collection algorithm used, and any internal optimization of the Java virtual machine instructions (for example, translating them into machine code) are left to the discretion of the implementor. [emphasis mine]