For some time we have been thinking to migrate from jdk1.5 to jdk 1.8 for performance reasons
Would that be an ideal thing to do in your opinion?Have you dealt with this kind of scenario in your book?
Which specific performance reasons do you have in mind? JDK 1.5 (and even 1.6) is EOLed long back, so it's ideal to move to Java 8 if that's an option. Or at the very least Java 7.
The book does not cover migration issues. However, I would recommend identifying those features in the newer versions of Java your application domain could benefit from, learn them, and find out the best way of applying them. While 1.5 is old, it is not as bad as one company I know which is still using Basic. And I don’t mean Visual Basic!
I don't think we can get any performance benefit just by moving from java 5 to java 8. We will have to look at code if newer and better performant APIs are available.
Sorry I was wrong. There have been perfomance improvements in Hotspot JVM and newer garbage collection algorithms in java 7 and I beleive that they will also be available in java 8.