content: Although there are only a few books currently discussing about the internal of JVM, this book is the worst of them. It copies too many pages such as the bytecode semantics from the JVM specification by Sun Microsystems and these parts consume around half of the books. Also most contents not borrowed from JVM specification is far too simple to be an indepth discussion of JVM. It only took me 2 hours to read the whole book and to find out that it is a bad book.