Understanding java multithread programming

Question

Hi
I am new to java multithreaded programming.
In order to understand more about threading mechanism, I would like to first know more about the processors,operating systems.
Please let me know which book or web site to follow to get a brief but good idea about processors,operating systems that would eventually let me go further with the understanding of multithreading mechanism in java.
Any input is highly appreciated.
Thanks in advance.

Answer 1

Multithread programming is a difficult topic.
If you protect every access to shared memory by using synchronized methods, you are on the safe side.
But things are not so simple in the real world.
Sooner or later, you will face deadlock problems, for instance, and you will learn how to avoid them.
With more experience, you will be tempted to use some "tricks" that you will find on the internet ( double-locking idiom or things like that ), not understanding why it is dangerous and does not work.
If you continue your investigation, you will end up with concepts such as memory barrier, race conditions, spinlocks, mutexes, memory model, processor cache and SMP, instruction reordering, and more.
( google some of these topics how wide the landscape is )
In fact, the more you work with it, the more you will have questions about it, and the more you will want to learn about it.
I also thought that multithreading was easy, three years ago, but it is not true.
Today, I continue to read books about it.
Read a lot ! The topic is wide, but the more you know about it, the best you can use it and be confident with it !
It is worth the effort, as multithreading is here to stay and seems to be everywhere.
Multithreading is difficult to understand fully, but very interesting.
Besides, if you write code for server programs ( serving multiple clients ), you must be aware of it.
Eventually, you will perhaps read this book:
UNIX(R) Systems for Modern Architectures: Symmetric Multiprocessing and Caching for Kernel Programmers
by Curt Schimmel
It is not about java, but if you want to really understand java, you must learn about the underlying layers, and even how a processor works.
As an example of what not to do and that I saw in an introductory book about java, the following code is full of bugs and does not work !
You cannot stop the looping thread B by just setting and testing a global flag like that.
static int stopflag = 0;
Thread A:
public void stop_B_thread()
stopflag = 1;
Thread B:
while (stopflag == 0)
// do some job